Physiological and biochemical changes in soybean as affected by organic, chemical and integrated nutrient management practices

A field experiment was conducted for three consecutive years (2004–2006) to study the relative effect of organic, chemical and integrated nutrient management practices on physiological and biochemical changes in soybean. The study revealed that chemical nutrient management practice (CNMP) recorded higher chlorophyll and LAI. The photosynthetic rate was slightly higher in organic nutrient management practice (ONMP) than CNMP and integrated nutrient management practice (INMP) in the later years. On an average, the dry matter accumulation (DMA) was higher in CNMP and INMP than ONMP. The nitrate reductase activity (NRA) was higher in INMP in the first year whereas in the second and third years, it was higher in ONMP. Though the number of nodules was not affected by different nutrient management practices in the first two years, in the third year ONMP recorded significantly higher number of nodules. In the initial years, CNMP recorded higher seed yield than both ONMP and control. In the third year, ONMP recorded higher seed yield. The oil and mineral content of soybean was not affected significantly in all the three years of study. In conclusion, the growth and productivity of soybean was lower in ONMP in the initial years, but had recovered over a period of time.