CHAPTER V
DISCUSSION
The salient findings emerging out of the study have been discussed in this section. Efforts have been made to support the findings with the published work of various scientists. Before discussing the growth and yield performance of crops in the sequence it is important to discuss the climatic conditions. The mechanical and chemical analysis of soil revealed that it was loam in texture, medium acidic in pH and low in organic carbon content. It was medium in available nitrogen and phosphorus while low in available potassium.
It was observed from the meteorological data presented in Table 2 that mean annual rainfall was 4648.9 mm and 2412.2 mm received in 97 and 125 rainy days in 2000 and 2001, respectively. The relative humidity was in the range of 62.60 to 94.45% and 66.75 to 90.55%. The temperature during crop growing seasons were in the range of 27.2 to 32.70C for maximum and 11.3 to 22.00C for minimum during 2000-2001 and in 2001-2002 it was in the range of 26.3 to 33.40C for maximum and 11.7 to 23.20C for minimum. Thus the climatic conditions were normal for growth of kharif hybrid rice and rabi mustard during both the years.
The results of the present investigation involving different fertilizer treatments showed great impact on grain and straw yield of hybrid rice during both the years. The beneficial effect in respect of grain yield was more prominent with Fertilizers 150:75:75 kg ha-1 (69.36 and 71.34 q ha-1) followed by application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia (68.31 and 71.02 q ha-1) and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia (66.9 and 68.94 q ha-1) during 2000 and 2001, respectively. The next best treatments were 90 kg UB-DAP ha-1, Fertilizers 100:50:50 kg ha-1, 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. All the treatments were significantly superior over control. Many workers have demonstrated identical results with different combinations of organic and inorganic sources of nutrients (Shinde, 1995). Similar results were also reported by Jindal and Kalia (1971); Purushothaman and Palaniappan (1978) and Jha et al. (1980). The beneficial effects of gliricidia leaves incorporation may be due to higher nitrogen content (2.75% N) and narrow C:N ratio of 13 besides having low lignin and polyphenol content the decomposition is very fast in the soil and mineralized nitrogen tends to become available within 10-15 days after incorporation (Kadam et al., 1986). An integrated nutrient management with combination of gliricidia and fertilizer helped to reduce 50% N of fertilizer dose. Bal et al. (1993) also reported the possibility of saving 50% dose of fertilizers through integrated use of fertilizers and green manures. Hybrid rice responded favorably to addition of gliricidia as a substitute for 50% dose of nitrogen. Application of 50% of nitrogen through 5 t ha-1 gliricidia significantly increased the grain yield of hybrid rice compared with the control. Though gliricidia contains low N (2.75%) its nutrients are in balanced and mineralized form (Raju et al., 1993). These results provided evidence to the belief that about 50% fertilizers could be saved with the combined use of fertilizers and gliricidia in rainy season crop of hybrid rice in South Konkan region. Setty and Gowda (1997) reported similar beneficial effect of integrated nutrient management in rice based cropping systems.
In case of straw yield, application of Fertilizers 150:75:75 kg ha-1 recorded the highest yield of 70.62 and 73.3 q ha-1 followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia (69.75 and 73.15 q ha-1), Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia (68.18 and 71.01 q ha-1), 90 kg UB-DAP ha-1 (67.31 and 69.02 q ha-1) and Fertilizers 100:50:50 kg ha-1 65.64 and 68.31 q ha-1 during 2000 and 2001, respectively and proved significantly superior over 60 kg UB-DAP ha-1, 10 t ha-1 gliricidia alone and control. Higher yield due to combined application of chemical fertilizers and gliricidia may be attributed to sustained nutrient supply and also as result of better utilization of applied nutrients through improved micro environmental conditions, especially the activities of soil micro organism involved in nutrient transformation and fixation. Similar results were also reported by Panda et al. (1995); Sawant (1995) and Chinnusamy et al. (1997).
The pooled analysis of two years data indicated that application of Fertilizers 150:75:75 kg ha-1 (70.35 q ha-1 of grain and 71.95 q ha-1 of straw yield) followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia resulted in significantly higher grain (69.66 q ha-1) and straw yield of (71.45 q ha-1) in hybrid rice over that of control. The next best treatments were 90 kg UB-DAP ha-1, Fertilizers 100:50:50 kg ha-1, 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. Similarly Fertilizers 150:75:75 kg ha-1 recorded 95.96 and 106.99% higher grain and straw yield of hybrid rice over that of control, respectively. It was closely followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia (94.04 and 105.55%) and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia with 89.19 and 100.20% increase over that of control. All the treatments were significantly superior to that of control. The beneficial effect of green manure was mainly due to steady release of nitrogen during crop season, which was utilized by the crop resulting into increased values of yield contributing characters and finally the yield. Such types of results were also reported by Daftardar et al. (1997); Talashilkar and Chavan (1997) and Turkhede et al. (1998).
The results of the present investigation involving gliricidia showed great impact on the growth characters and yield of hybrid rice. The beneficial effects were more prominent with combined application of gliricidia and fertilizers, which can be explained in the light of growth and yield contributory characters. Height of plant (cm), number of functional leaves and dry matter accumulation per hill at various growth stages clearly brought out the superiority of application of Fertilizers 150:75:75 kg ha-1 and Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia.
The maximum plant height was recorded due to fertilization with Fertilizers 150:75:75 kg ha-1 followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia at all the stages of growth of hybrid rice during both the years, except at 60 DAT during second year. The next best treatments were Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 90 kg UB-DAP ha-1, 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. All the treatments were significantly superior over control. Similar results were also shown by Reddy et al. (1972); Sheela and Thomas (1995) and Talathi (2001). Fertilization with Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia produced the maximum numbers of tillers per hill at all the stages of crop growth of hybrid rice followed by Fertilizers 150:75:75 kg ha-1, 90 kg UB-DAP ha-1, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 100:50:50 kg ha-1 of hybrid rice during both the years except at 60 DAT. The next best treatments were 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. All the treatments were significantly superior over control. Thus might be due to addition of green manures, which add organic manures and nitrogen to the soil helping in enhanced plant height as well as number of tillers per hill of plant. Nutrient availability increases due to production of carbon dioxide and organic acids during decomposition of green manure, which help in good growth of the plant. The results are agreeing with Jaggi and Russel (1973); Jamdade and Ramteke (1986) and Jaychandran and Veerabadran (1996).
The maximum number of functional leaves per hill was produced due to Fertilizers 150:75:75 kg ha-1 followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia at all the stages of crop growth of hybrid rice during both the years. The next best treatments were Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 90 kg UB-DAP ha-1, 10 t ha-1 gliricidia alone and 60 kg UB-DAP ha-1. All the treatments were significantly superior over control. These results are in conformity with the work of Talathi (2001). The dry matter accumulation is considered to be the reliable index of crop growth and was significantly influenced due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia during 2001. Application of Fertilizers 150:75:75 kg ha-1 registered maximum dry matter accumulation per hill during 2000 except at 60 DAT, while Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia showed maximum dry matter accumulation per hill during 2001 except at 30 DAT. The next best treatments were Fertilizers 100:50:50 kg ha-1, Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, 60 kg UB-DAP ha-1, 90 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. All the treatments were significantly superior over control. These results are similar to those reported by Bhardwaj et al. (1981); Maskina et al. (1989) and Shinde (1995).
Higher dry matter accumulation in hybrid rice plant further led to the proportionate improvement in yield contributory characters like number of panicles per hill, length of panicle (cm), number of filled grains per panicle and weight of filled grains per panicle during both the years. The numerical values of all these characters were higher with application of Fertilizers 150:75:75 kg ha-1 during both the years, but the differences due to former treatments with Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia were of similar order in most of the characters. Application of Fertilizers 150:75:75 kg ha-1 noted maximum number of panicles per hill, length of panicle, number of filled grains per panicle and weight of filled grains per panicle during both the years followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia. The next best treatment in case of number of panicles per hill was 90 kg UB-DAP ha-1. Application of Fertilizers 100:50:50 kg ha-1 did not show marked variation with Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, while 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone were not significant in most of the characters. These results are similar to those reported by Balasubramaniyan and Palaniappan (1989), Kanungo and Roul (1994) and Gangwar and Sharma (1996). Better performance of combined use of gliricidia with chemical fertilizers might be due to synergistic effect of fertilizers and gliricidia as well as the slow release of nutrients throughout the crop growth thus helping to form more photosynthetic compounds and translocation of the same from source to sink (Peeran and Ramulu, 1995). Matiwade and Sheelavanter (1994) observed that grain yield is essentially the manifestation of yield contributing characters of crops. Higher yielding ability of hybrid rice with green manures coupled with fertilizers attributed to higher number of filled grains per panicle, length of panicle and weight of filled grains per panicle. Jamdade and Ramteke (1986) also observed increased number of panicles with the combined application of fertilizers with green manures. The improvement in yield contributing characters due to various green manures may be because of the improvement of physical properties and chemical composition of soil and availability of plant nutrients for longer time as indicated by Jamdade (1985). The superiority of gliricidia was mainly due to low C:N ratio i.e. 15:1. Unfertilized plots showed maximum number of unfilled grains per panicle followed by 10 t ha-1 gliricidia alone and 60 kg UB-DAP ha-1 during both the years. These results confirmed with the findings of Talathi (2001). Application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia showed highest Thousand grain weight (g) followed by 90 kg UB-DAP ha-1, Fertilizers 150:75:75 kg ha-1 and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia during both the years. These results are in line with those conformed by Bal et al. (1993); Verma and Bhagat (1994) and Gangwar and Sharma (1996).
Studies on nutrient uptake further supported the superiority of combined application of fertilizers and gliricidia over application of fertilizer dose alone. Application of Fertilizers 150:75:75 kg ha-1 noted maximum nitrogen uptake followed by application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, which were similar with each other. The next best treatments were 90 kg UB-DAP ha-1, Fertilizers 100:50:50 kg ha-1, 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. All the treatments were significantly superior over control. These results are in conformity with Kumar et al. (1989); Sawant et al. (1993) and Sawant (1998). This might be due to slow and continuous supply of nutrients to hybrid rice plant as required by the plants due to bio-green influence on chemical nitrogen as suggested by Peeran and Ramulu (1995). Chatterjee et al. (1979) also indicated that the inorganic nitrogen source applied in combination with organic sources is better utilized than inorganic source of nutrient alone. The nitrogen uptake by hybrid rice is governed by its concentration in plants and dry matter accumulation. Beneficial effect of combined application green manures and inorganic source of fertilizers in hybrid rice crop supported the observation of Gill et al. (2000). It was evident that higher uptake of the nutrients by the crop has contributed towards the increased grain yield, which was not seen in the control treatment (no gliricidia or fertilizers).
In case of phosphorus uptake by hybrid rice grain and straw, application of Fertilizers 150:75:75 kg ha-1 showed the highest uptake during both the years. The next best treatments were Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, 90 kg UB-DAP ha-1, Fertilizers 100:50:50 kg ha-1, 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. All the treatments were significantly superior over control. These results are in conformity with the results noted by Menon et al. (1990); Sawant (1998) and Talathi (2001). The additional phosphorus supplied by gliricidia and its influence on solubilizing native phosphorus might have resulted into increase in phosphorus uptake in the treatments with gliricidia. The improvement in phosphorus uptake by grain and straw in the treatments receiving 50% N substitution through gliricidia may also be due to significant synergistic effect of an application of organic matter on phosphorus utilization by the hybrid rice crop. These results are in agreement with those observed by Jadhav (1989).
Potassium uptake by hybrid rice grain and straw showed that the application of Fertilizers 150:75:75 kg ha-1 recorded the highest value followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia during both the years. The next best treatments were 90 kg UB-DAP ha-1, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 60 kg UB-DAP ha-1 and 10 t ha-1 gliricidia alone. All the treatments were significantly superior over control. These results are in conformity with Talathi (2001). The enhanced potassium absorption in the gliricidia treatments may be due to increased supply of potassium by organic matter and increase in the concentration of potassium in hybrid rice plant in the corresponding treatments. This also proved superiority of application of fertilizers in conjunction with gliricidia over the inorganic fertilizers alone. Similar positive effect on potassium uptake due to incorporation of organic manures has been reported by several workers (Patil, 1985). This proved that combined application of green manures with chemical fertilizers enhanced the hybrid rice production through improved nutrient uptake. Consistent results were also reported by Jamdade (1985); Patil et al. (1985) and Yadav (1998). By and large the trend of nutrient uptake very well resembled with the per hectare yield data of the various treatments. The enhanced uptake of these nutrients in those treatments could be due to increased and sustained availability of nutrients influenced by the green manures under better physical, chemical and biological condition of soil created by the green manures (Jadhav, 1989).
It is further justified with the studies on physical properties viz., bulk density and water holding capacity. Data showed that gliricidia alone and combined with fertilizers in general, had a beneficial effect on these properties compared to fertilizers alone after harvest of hybrid rice. The results further indicated that application of 10 t ha-1 gliricidia alone recorded the lowest bulk density and the highest water holding capacity as compared to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and chemical fertilizers alone. This was mainly attributed due to application of additional quantity of green manures destroying the development of hard pan in soil helping into lowering down the bulk density. Decrease in bulk density may be partly attributed to the increase in porosity and high accumulation of green matter (Malewar and Hasnabade, 1995). The differences between the treatments were significant in terms of bulk density and water holding capacity during both the years. The results were in line with those obtained by Bhatia and Shukla (1982); Garg et al. (1991) and Ramteke et al. (1998).
The bulk density of soil after harvest of hybrid rice showed that application of Fertilizers 150:75:75 kg ha-1 had significantly higher values during both the years. The next best treatments were 90 kg UB-DAP ha-1, Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, control, Fertilizers 100:50:50 kg ha-1 and 60 kg UB-DAP ha-1. All the treatments were significantly superior over 10 t ha-1 gliricidia alone. These results are in conformity with Havangi and Mann (1970) and Biswas et al. (1971). Bavaskar and Zende (1973) reported that this may be due to application of additional quantity of organic manures destroying the development of hard pan in soil thus helping in lowering down the bulk density. Similar results were also noted by Gattani et al. (1976); Chatterjee et al. (1979) and Prasad and Singh (1980). Many workers like Shanmugam and Ravi (1980); Kapur et al. (1981) and Bhatia and Shukla (1982) noted that there was increase in the bulk density due to chemical fertilizer alone mainly due to deterioration of structure by nitrogenous fertilizers. Garg et al. (1991); Sur et al. (1993) and Sharma and Sharma (1993) revealed that the decrease in bulk density was partly attributed to the increase in porosity and high accumulation of organic matter. Yin-Po-Wang and Chen-Ching-Cho (1995); Kumar and Singh (1997) and Mishra and Sharma (1997) also reported similar results. In the case of water holding capacity of soil after harvest of hybrid rice, it was observed that 10 t ha-1 gliricidia alone had significantly highest value followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia during both the years. The next best treatments were Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 150:75:75 kg ha-1, control, 60 kg UB-DAP ha-1, Fertilizers 100:50:50 kg ha-1 and 90 kg UB-DAP ha-1. Thus, green manuring improved soil structure and increased water holding capacity. Similar type of results was also noticed by Sharma et al. (1988); Garg et al. (1991) and Sur et al. (1993).
Chemical studies on soil showed a significant variation in organic carbon content during both the years after harvest of hybrid rice. The positive effect of balanced fertilization on improvement in organic carbon content of the soil was enhanced, when chemical fertilizers were applied in conjunction with green manures. 10 t ha-1 gliricidia alone recorded the highest organic carbon content after harvest of hybrid rice during both the years followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia. The next best treatments were Fertilizers 150:75:75 kg ha-1, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 90 kg UB-DAP ha-1 and 60 kg UB-DAP ha-1. All the treatments were significantly superior over control. Similar results of increase in organic carbon content with application of green manures have been reported earlier by Acharya et al. (1988) and Biswas et al. (1971). The increase in soil organic carbon content with application of green manures has also been reported by Mishra and Sharma (1997). The results of the present investigation are in conformity with Kanwar and Prihar (1962); Biswas et al. (1971) and Singh et al. (1980). Prasad and Singh (1980) stated that this may be due to decomposition and mineralization of organic matter. Minhas and Mehta (1984); Rayer (1984) and Kim et al. (1985) reported similar results.
Studies on available nitrogen status of the soil after harvest of hybrid rice showed that all the fertilized plots had higher available nitrogen than the unfertilized plot during both the years. It is to be noted that combined application of inorganic fertilizers and gliricidia showed improvement in available nitrogen as compared to application of fertilizers alone after harvest of hybrid rice during both the years. The highest available nitrogen was due to Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia (322.04 kg ha-1) during 2000 and Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia (363.84 kg ha-1) during 2001 followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia (317.47 kg ha-1) and Fertilizers 150:75:75 kg ha-1 (358.99 kg ha-1) during 2000 and 2001, respectively, which was mainly ascribed to green leaf residues and higher nitrogen content in gliricidia leaves (Kanwar and Prihar, 1962). Maximum gain of nitrogen in soil after hybrid rice was due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 150:75:75 kg ha-1, 10 t ha-1 gliricidia alone, 90 kg UB-DAP ha-1 and Fertilizers 100:50:50 kg ha-1. 60 kg UB-DAP ha-1 and control showed negative balance. These type of results were also observed by Kadam et al. (1986); Acharya et al. (1988) and Jayaraman (1988). Mandal et al. (1982); Prasad (1994) and Acharya et al. (1988) reported that integrated use of NPK + green manure improved the available nitrogen status of soil to a maximum extent, which might be due to higher mineralization rate of soil nitrogen caused due to greater multiplication of soil microbes resulting into higher nitrogen availability. This contribution of nitrogen by green manure could be attributed as one of the reason for increasing the yield of hybrid rice under these treatments.
After harvest of hybrid rice there was appreciable build up in available phosphorus status in soil due to fertilizer alone or in combination with green manures during both the years, which is largely attributed to minimization of phosphorus fixation and fertilization. Application of Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia did not improve the available phosphorus of soil to a significant extent as compared to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, but these were significantly superior over control. Maximum gain of available phosphorus in soil after hybrid rice was due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia followed by Fertilizers 150:75:75 kg ha-1, 10 t ha-1 gliricidia alone and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia. Application of Fertilizers 100:50:50 kg ha-1, 90 kg UB-DAP ha-1, 60 kg UB-DAP ha-1 and control showed negative balance. Singh and Brar (1985); Singh and Singh (1987) and Talathi et al. (2002) noticed the similar findings. The integrated use of NPK + gliricidia together consistently ensured significantly higher available phosphate status of soil as compared to all the other treatments, which might be due to the continuous supply of phosphorus though gliricidia. Similar results were also obtained by Singh et al. (1988). The effect of gliricidia in this respect was superior, which might be because of its low phosphate content (0.51%). Further, integrated use of NPK + gliricidia showed very prominent increase in available phosphorus compared to Fertilizers 100:50:50 kg ha-1 alone perhaps owing to the mineralizing the organic phosphorus contributing to its accumulation in the soil and secondly gliricidia also helped to enhance the availability of native as well as added phosphate. Biswas et al. (1971) on loamy sand soil of Ludhiana observed that application of organic manures in conjunction with NPK increased the available phosphorus status of soil. This may be due to liberation of many organic acids during decomposition process resulting in to solubilization of insoluble phosphate.
In spite of constantly higher yields obtained in the treatments where green manures were applied in conjunction with fertilizers there was improvement in available potassium status of soil over the initial value after harvest of hybrid rice during both the years, which may be attributed to acidulation as a result of decomposition of organic matter and release of mineral potassium in soil solution (Malewar and Hasnabade, 1995). Application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia (134.01 and 141.57 kg ha-1) and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia (120.40 and 121.33 kg ha-1) noted higher available potassium status in soil during 2000 and 2001, respectively. Maximum gain of available potassium in soil after hybrid rice was due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, 10 t ha-1 gliricidia alone, 90 kg UB-DAP ha-1, Fertilizers 100:50:50 kg ha-1, Fertilizers 150:75:75 kg ha-1 and 60 kg UB-DAP ha-1. Negative balance was only shown by control. This was seen by Singh and Brar (1985); Acharya et al. (1988) and Talathi et al. (2002). Maximization in grain as well as straw yield has reflected into higher net returns due to fertilizers as well as combination of fertilizers and gliricidia. This indicated that combined use of gliricidia and fertilizers had definitely positive effect in enhancing potassium availability. Sharma and Sharma (1993) opined that increased availability of potassium was mainly due to displacement of potassium from clay by ammonium under submerged condition and also aided by liberated acids due to decomposition of green manures.
Hybrid rice grown with application of 90 kg UB-DAP ha-1 and Fertilizers 150:75:75 kg ha-1 proved highly remunerative compared to all other treatments recording a net returns of Rs. 15752.17 ha-1 and Rs. 14968.24 ha-1, respectively followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia (Rs. 14929.62), Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia (Rs. 14305.87), Fertilizers 100:50:50 kg ha-1 (Rs. 13437.20) and 60 kg UB-DAP ha-1 (Rs. 11665.38). The lowest net profit was noted due to 10 t ha-1 gliricidia alone (Rs. 10851.82), while negative net profit was recorded due to unfertilized plots (-2593.88). The highest benefit cost ratio of 1.56 was found in 90 kg UB-DAP ha-1 followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia (1.50), Fertilizers 150:75:75 kg ha-1 (1.47) and Fertilizers 100:50:50 kg ha-1 (1.45) and Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia. Similar results were also observed by Talathi (2001).
Mustard is of great significance in a region like Konkan where water is limiting factor and thus an efficient use of water is of great importance Therefore, the crop of mustard variety ‘Varuna’, which can give maximum yield under available resource will be a very useful agricultural strategy of oilseed production in Konkan region during rabi season.
Mustard crop with the residual effect of preceding treatments on grain yield, stover yield of rabi mustard noted that application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia proved its superiority followed by Fertilizers 150:75:75 kg ha-1, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 10 t ha-1 gliricidia alone, 90 kg UB-DAP ha-1, 60 kg UB-DAP ha-1 and control during both the years. All the treatments were significantly superior over 60 kg UB-DAP ha-1 and control. Thus results showed that residual effect of combined use of fertilizers and gliricidia played an important role in the performance of treatments in mustard. This type of trend was also reported by Roy et al. (1981); Vaidya et al. (1981) and Arthamwar et al. (1996).
In the case of residual effect of preceding treatments on rabi mustard the maximum plant height was recorded due to Fertilizers 150:75:75 kg ha-1 followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia at all the stages of growth of mustard, except at 90 DAT during both the years. The next best treatments were 90 kg ha-1 UB-DAP, Fertilizers 100:50:50 kg ha-1, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, 60 kg UB-DAP ha-1, 10 t ha-1 gliricidia alone and control. Similar results were also noted by Dongale et al. (1990) and Patel and Shelke (1998). Mustard crop grown after application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia produced the maximum numbers of branches per hill at all the stages of crop growth followed by Fertilizers 150:75:75 kg ha-1 and 90 kg UB-DAP ha-1 during both the years. The next best treatments were Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 60 kg UB-DAP ha-1, 10 t ha-1 gliricidia alone and control. Similar results have been reported by Dongale et al. (1990) and Kumar and Bhogal (2000).
The residual effect of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 150:75:75 kg ha-1 and 90 kg UB-DAP ha-1 were of similar magnitude and significantly superior over Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 10 t ha-1 gliricidia alone, 60 kg UB-DAP ha-1 and control during both the years in respect of number of leaves of mustard at 30 and 60 DAS. This was also reported by Dongale et al. (1990); Tomar et al. (1996) and Patel and Shelke (1998). The highest dry matter accumulation at all the stages of crop growth of mustard was due to residual effect of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia followed by Fertilizers 150:75:75 kg ha-1 and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and were significant over all other treatments during both the years. The next best treatments were Fertilizers 100:50:50 kg ha-1, 10 t ha-1 gliricidia alone, 90 kg UB-DAP ha-1, 60 kg UB-DAP ha-1 and control. This was also reported by Vir and Verma (1979); Mudholkar and Ahlawat (1981) and Patel and Shelke (1998). In the case of residual effect of preceding treatments on rabi mustard Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia produced highest number of siliquae per plant, length of siliquae, number of grains per siliqua, weight of siliquae (g) per plant, weight of grains per plant and thousand grain weight of mustard followed by Fertilizers 150:75:75 kg ha-1 and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and were significant over all other treatments during both the years. The next best treatments were Fertilizers 100:50:50 kg ha-1, 10 t ha-1 gliricidia alone, 90 kg UB-DAP ha-1, 60 kg UB-DAP ha-1 and control. The growth characters enhanced by the residual effect of treatments showed an enhanced effect on the yield contributing characters of mustard. Green manures release nutrients after their decomposition, which helps to increase the soil fertility ultimately boosting the growth of succeeding crop. This was also reported by Singh and Moolani (1969); Bhan and Singh (1975) and Roy and Tripathi (1983).
In the case of nitrogen uptake in the residual effect of preceding treatments on rabi mustard by mustard grain and stover Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia recorded significantly highest uptake followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 150:75:75 kg ha-1. The next best treatments were 10 t ha-1 gliricidia alone, Fertilizers 100:50:50 kg ha-1, 90 kg UB-DAP ha-1 and 60 kg UB-DAP ha-1. All the treatments were significantly superior over control. Similar results were reported by Ilin (1986). In the case of phosphorus uptake in the residual effect of preceding treatments on rabi mustard by mustard grain, Fertilizers 150:75:75 kg ha-1 recorded highest uptake followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia during first year while during second year Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia was highest followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 150:75:75 kg ha-1 and were significantly superior over all other treatments during both the years. All the treatments were significantly superior over control. This was also reported by Roy and Tripathi (1983) and Ilin (1986). Application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia recorded highest potassium uptake followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 150:75:75 kg ha-1 during first year the next best treatments were 10 t ha-1 gliricidia alone, Fertilizers 100:50:50 kg ha-1, 90 kg UB-DAP ha-1, 60 kg UB-DAP ha-1 and control while during second year Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia was highest followed by Fertilizers 150:75:75 kg ha-1 and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and the three were significantly superior over all other treatments during both years. All the treatments were significantly superior over control. The beneficial effect of gliricidia is reflected in the uptake of nutrients by plants. Thus, it can be seen that the combination of fertilizers and gliricidia has increased the uptake of nitrogen, phosphorus and potassium in mustard. These types of reports were also reported by Roy and Tripathi (1983) and Ilin (1986).
Mustard grown after the hybrid rice crop fertilized with Fertilizers 150:75:75 kg ha-1 recorded significantly higher oil production followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1, 90 kg UB-DAP ha-1, 60 kg UB-DAP ha-1, 10 t ha-1 gliricidia alone and control. Similar results have also been reported by Roy et al. (1981); Arthamwar et al. (1996); Tomar et al. (1996) and Kumar and Bhogal (2000). The residual effect of preceding treatments enhanced the protein yield of rabi mustard. The application of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia was significantly superior over all other treatments followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, which were also significantly superior over other treatments during both years. The next best treatments were Fertilizers 150:75:75 kg ha-1, 10 t ha-1 gliricidia alone, 90 kg UB-DAP ha-1, Fertilizers 100:50:50 kg ha-1 and 60 kg UB-DAP ha-1. All the treatments were significantly superior over control. The higher uptake of nutrients by grain in mustard ultimately increased the quality characters of mustard. Thus the use of gliricidia reflected in the enhanced oil production as well as protein yield. These results are in conformity with the work by Kumar and Bhogal (2000).
The residual effect of preceding treatments did not affect the bulk density of soil after mustard during both years. Increase in WHC was mainly attributed to decrease in bulk density due to green manures in the said treatment. Similar findings were also reported by Kapur et al. (1981); Sur et al. (1993) and Ramteke et al. (1998). In general, 5 t ha-1 gliricidia helped to improve the soil physical conditions through excreted microbial cells, decomposition products and penetration of fine roots, which acts as a binding agent. Thus, these observations clearly pointed out that use of 5 t ha-1 gliricidia with 50% nitrogen through fertilizers is a judicious blend to maintain soil fertility and desirable soil physical condition for sustainable crop productivity. The residual effect of 10 t ha-1 gliricidia alone was significant over all the other treatments during both the years in case of WHC of soil after harvest of mustard followed Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia. The next best treatments were Fertilizers 150:75:75 kg ha-1, control, 60 kg UB-DAP ha-1, 90 kg UB-DAP ha-1 and Fertilizers 100:50:50 kg ha-1. Similar results have been reported Gattani et al. (1976); Garg et al. (1991) and Dongre (1997).
The residual effect of 10 t ha-1 gliricidia alone was the highest in case of organic carbon content after mustard followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia. The next best treatments were Fertilizers 100:50:50 kg ha-1, Fertilizers 150:75:75 kg ha-1, 60 kg UB-DAP ha-1, 90 kg UB-DAP ha-1 and control. Similar results were also reported by Kanwar and Prihar (1962); Biswas et al. (1971) and Singh et al. (1980). Prasad and Singh (1980) opined that this may be due to decomposition and mineralization of organic matter. This was also confirmed by Rabindra and Gowda (1986); Jayaraman (1988) and Bhandari et al. (1992).
Maximum gain of nitrogen in soil after harvest of mustard was due to Fertilizers 150:75:75 kg ha-1 applied to the preceding crop of hybrid rice followed by Fertilizers 100:50:50 kg ha-1, Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia and 90 kg UB-DAP ha-1. The negative balance was observed due to residual effect of 60 kg UB-DAP ha-1, 10 t ha-1 gliricidia alone and control. Singh and Brar (1985); Prasad et al. (1986) and Blanc et al. (1989) noted the similar observations. Maximum gain of available phosphorus in soil in the case of residual effect of preceding treatments on rabi mustard after harvest of mustard was due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia followed by Fertilizers 150:75:75 kg ha-1 and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia. Application of 10 t ha-1 gliricidia alone and control showed negative balance. Similar results were also noticed by Singh and Brar (1985); Singh and Singh (1987) and Acharya et al. (1988). Similarly maximum residual gain of available potassium in soil was due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia followed by Fertilizers 150:75:75 kg ha-1 and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia, Fertilizers 100:50:50 kg ha-1 and 10 t ha-1 gliricidia alone. Thus it can be derived that gliricidia increased the availability of nutrients in soil. This was also noticed by Singh and Brar (1985) and Acharya et al. (1988).
The growth is function of metabolic processes in plants and the rate of metabolic processes is an indication of growth. Nitrogen is an important element in accelerating the metabolic processes. The farmer is interested in economic yield. The farmer needs a fertilizer schedule which results in higher yield because yield in a crop provides a measure of proportion of grains related to the total dry matter accumulation. It is therefore important to study how the fertilizers affect the yield contributing characters and yield of mustard.
The increase in fertilizer dose had pronounced effect on the grain and stover yield of mustard. It was noted that application of Fertilizers 90:45:45 kg ha-1 recorded significantly higher yield of 11.14 and 11.15 q ha-1 followed by Fertilizers 45:45:45 kg ha-1 (10.68 and 10.62 q ha-1) and control (9.24 and 9.07 q ha-1) during 2000-2001 and 2001-2002, respectively. In the pooled means Fertilization with Fertilizers 90:45:45 kg ha-1 produced 21.86 and 23.84% more grain and stover yield than control, while applying Fertilizers 45:45:45 kg ha-1 noted 16.39 and 19.29% more grain and stover yield than control. These findings agree with the results obtained by Bhan and Singh (1975); Dhillon and Vig (1985) and Zaman (1985).
The plant population per plot was not significantly affected due to different treatments during both the years. The data in case of height, number of branches per plant, number of leaves per plant, dry matter accumulation of mustard showed a typical sigmoid trend. The mustard variety ‘Varuna’ responded well to the nitrogen fertilization. The growth characters mentioned earlier increased with increasing levels of fertilization. Plants receiving the highest dose of Fertilizers 90:45:45 kg ha-1 recorded maximum values followed by Fertilizers 45:45:45 kg ha-1 and control. These results are in agreement with those obtained by Tomar et al. (1996); Patel and Shelke (1998) and Kumar and Bhogal (2000).
The data regarding number of siliquae per plant, length of siliquae, number of grains per siliqua, weight of siliquae (g) per plant, weight of grains and thousand grains weight per plant revealed that all these characters were enhanced due to increasing levels of fertilizers. Application of Fertilizers 90:45:45 kg ha-1 recorded higher values followed by Fertilizers 45:45:45 kg ha-1 and control. These findings are in agreement with those reported by Roy and Tripathi (1983); Dongale et al. (1990) and Patel and Shelke (1998). The uptake of nitrogen, phosphorus and potassium by mustard grain and stover as affected by different fertilizer doses indicated that the uptake increased with the successive levels of fertilizers. Application of Fertilizers 90:45:45 kg ha-1 recorded the highest uptake followed by Fertilizers 45:45:45 kg ha-1 and control. These findings are in agreement with those obtained by Roy and Tripathi (1983) and Ilin (1986).
A glance at the data regarding the quality of mustard grain recorded in terms of per cent oil content and per cent protein content clearly indicated the superiority of higher doses of fertilizer nutrients. The application of higher level of nitrogen resulted in decreased oil content and increased protein content. This phenomenon can be explained by the fact that the increasing nitrogen increased the nitrogen content and ultimately the protein content at the cost of oil formation as nitrogen is a component of amino acids, which make the protein. In case of oil production and protein yield in mustard Fertilizers 90:45:45 kg ha-1 recorded significantly higher values followed by Fertilizers 45:45:45 kg ha-1 and control during both years. These findings are in confirmation with the results obtained by Roy et al. (1981); Ilin (1986); and Kumar and Bhogal (2000).
The application of fertilizers to mustard did not influence the organic carbon content of soil during first year while control had highest value followed by Fertilizers 45:45:45 kg ha-1 and Fertilizers 90:45:45 kg ha-1 during second year. Similar results are observed by Kanwar and Prihar (1962); Biswas et al. (1971) and Gattani et al. (1976); Prasad and Singh (1980) proved that this may be due to decomposition and mineralization of organic matter.
Application of Fertilizers 90:45:45 kg ha-1 registered the highest gain of nitrogen, while negative balance after harvest of mustard was observed due to application of Fertilizers 45:45:45 kg ha-1 and control. Similar results were also shared by Bhrigvanshi (1988); Blanc et al. (1989); Udayasoorian et al. (1989) and Mandal et al. (1991). Gain of phosphorus and potassium was highest due to Fertilizers 90:45:45 kg ha-1 followed by Fertilizers 45:45:45 kg ha-1 and control after harvest of mustard. Similar results were also shared by Bhrigvanshi (1988); Blanc et al. (1989); Udayasoorian et al. (1989) and Mandal et al. (1991). From these observations, a generalized statement can be made that the green manures not only improve the physical status of soil, but also enrich the soil in available nitrogen, phosphorus and potassium as compared to control. Improvement in fertility status of soil may be attributed due to addition of more biomass containing green nitrogen compounds to the soil, which might have been subsequently decomposed during the hybrid rice crop season (Khind et al., 1982).
In the case of economics of rabi mustard the interaction of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard and Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard proved highly remunerative compared to all other treatments recording a net profit of Rs. 24676.69 ha-1 and Rs. 24213.77 ha-1, respectively closely followed by Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (Rs. 23390.39) and Fertilizers 150:75:75 kg ha-1 to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (Rs. 23231.89). The lowest net return was observed in the case of unfertilized plot in hybrid rice as well as mustard (Rs. 4342.29). The highest benefit cost ratio of 3.72 was found in Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with no fertilizers to mustard followed by 3.65 in Fertilizers 150:75:75 kg ha-1 to hybrid rice with no fertilizers to mustard, Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with no fertilizers to mustard (3.43) and Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard (3.35). This is also reported by Valero and Haq (1986) and Dongale et al. (1990).
The data on balance of nutrients in hybrid rice-mustard cropping sequence indicated that Fertilizers 150:75:75 kg ha-1 to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard recorded the highest gain of 157.38 kg N ha-1, followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (145.59 kg ha-1). The highest negative nitrogen balance was in absolute control (-161.16 kg ha-1). Similar results were also observed by Rao and Sharma (1978). It was further observed that the maximum gain of phosphorus was due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (28.95 kg ha-1) followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard (25.73 kg ha-1) in hybrid rice-mustard cropping sequence. The maximum negative phosphorus balance was observed by absolute control (-15.50 kg ha-1). Similar results were also observed by Sakal et al. (1999). The maximum increase in potassium status to the extent of 106.46 kg ha-1 was recorded by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard (105.95 kg ha-1) while no fertilization (T1M1) to hybrid rice-mustard sequence resulted in to the net negative balance recording the highest net negative balance of 20.56 kg ha-1. Similar results were also observed by Sonar and Zende (1984).
In the case of economics of cropping system as a whole the highest net return was obtained due to Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (Rs. 38982.56) closely followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard (Rs. 38519.64), The lowest net return was recorded by control (Rs. 1748.51). The highest benefit cost ratio of 1.93 was found in Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard and Fertilizers 50:50:50 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard. Gangwar and Katyal (2001) also reported that in terms of minimum risk of financial involvement, rice-Indian mustard-rice was advisable. Singh et al. (2002) also reported that least B:C ratio was from control treatment. Similar results of higher monetary returns due to application of chemical fertilizers alone were also obtained by Sharma et al. (1988) in rice-wheat cropping system.
It was noticed that highest production potential was recorded due to Fertilizers 150:75:75 kg ha-1 to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (83.60 q ha-1). It was closely followed by Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (83.48 q ha-1) and Fertilizers 150:75:75 kg ha-1 to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard (83.10 q ha-1). The lowest production potential was seen in T1M1 (40.68 q ha-1). Similar results of due to application of chemical fertilizers and organic manures were also obtained by Talathi (2001) in rice-maize and rice-groundnut cropping systems.
The highest hybrid rice yield equivalent in the system was recorded due to combination of Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (196.90 q ha-1). It was closely followed by Fertilizers 150:75:75 kg ha-1 to hybrid rice with Fertilizers 90:45:45 kg ha-1 to mustard (195.91 q ha-1) and Fertilizers 75:75:75 kg ha-1 + 5 t ha-1 gliricidia to hybrid rice with Fertilizers 45:45:45 kg ha-1 to mustard (194.99 q ha-1). The lowest hybrid rice yield equivalent was seen in no fertilizers to hybrid rice as well as mustard (91.72 q ha-1). The data clearly indicated that gliricidia could substitute 50% N need of hybrid rice, which can economize the further nutrient requirement of succeeding mustard in a sequence without any detrimental effect on the productivity of the system. Hence the results by and large go in favor of replacing current sequence by hybrid rice-mustard cropping sequence. The results are in close conformity with those reported by Gill et al. (2000). The study has brought out the need for taking into cognizance the cropping sequence as a whole rather than individual crop. Thus, hybrid rice-mustard (cereal-oilseed) sequence has no doubt lead to increased grain production as the two crops have high productivity and less elements of risk, continuously cropping of existing sequence may bring adverse effects on soil health, which prove hazardous in the long run compared to hybrid rice-mustard sequence.
Thus hybrid rice-mustard cropping sequence has no doubt lead to increased grain production as the two crops have high productivity and less elements of risk and can bring desirable effects on soil health, which prove beneficial in the long run. Hence adopting hybrid rice-mustard cropping sequence with integrated nutrient management will be certainly beneficial to maintain the long term soil fertility and soil health in South Konkan region.
Implications of present research work on the future research work in lateritic soils of South Konkan region
In the present investigation gliricidia was applied to hybrid rice crop only and its residual effect on the succeeding mustard crop was studied. It is necessary to investigate the effect of different green manures applied to every crop in the sequence on the performance of the crops included in the sequence and its effects on soil properties. Experiment should be conducted to decide whether application of green manures should be done every year or in alternate years for sustaining soil fertility and productivity for different crop sequences.