Long-term impact of fertilizers and manures on Groundnut productivity under rainfed cultivation

The Permanent Manurial Trial on rainfed groundnut and cold weather gingelly was started in the field nos. B3, B4, B5 and B6 during 1991 at Oilseeds Research Station, Tindivanam. This trial is being carried out in Randomized Block Design with 12 treatments replicated four times. The groundnut crop is being taken up during Kharif and cold weather gingelly is taken up after the harvest of Kharif groundnut as Rabi cold weather gingelly. Kharif and rabi sowing with respective crops were carried out continuously. The soil is fine loamy typic Ustropept Tindivanam series. The nutrient potential of FYM was characterized before the application in every year. The N, P and K content varied between 0.39 to 0.40, 0.14 to 0.16 and 0.7 to 0.8 respectively. From the five years of research on Kharif groundnut and cold weather gingelly cropping system under pure rainfed condition without any supplemental irrigation revealed that, inputs applied as pure organic such as FYM or inorganic nutrient through fertilizers not produced maximum yield. But soil physical quality such as bulk density and pore space can be improved through the application of organic manures as compared to inorganic fertilizers. The soil microbial count also increased in the organic manures applied treatments. Integrated nutrient management through organic, inorganic and herbicide will give better yield along with no deterioration of soil quality. From the 5 years period of permanent manurial experiment (2015-2020) revealed that 100% NPK+FYM@12.5tha^-1+ Pendimethalin weedicide was applied @2 lit/ha. statistically superior than the other treatments with organic or inorganic source alone. So the general interpretation is that the treatments which received FYM alone or inorganic nutrients alone could not record statistically maximum yield, while the treatments that received 100% inorganic nutrients and 100% FYM topped in giving maximum yield under Kharif groundnut and cold weather gingelly.