Do groundnut as preceding crop reduce fertilizer requirement to the succeeding blackgram?-Results of field investigation

Intensive legume cropping system enhances the soil productivity and reduce the dependance on exterior inputs as legumes are well known for nitrogen (N) fixation by biological means. In addition, inorganic fertilizers, together with the integrated and careful use of FYM, could be an efficient option for increasing the productivity of the legume - legume cropping system. The common use of fertilizer and organics has been shown to have a synergistic effect on crop productivity, while simultaneously improving soil fertility. The residual effects of organic manures applied to previous crops may be available to subsequent crops. As a result, this experiment was designed to shed information on the usage of integrated nutrients from organic and inorganic sources on leguminous groundnut and the residual influence on subsequent blackgram.

During 2018-19, 2019-20 and 2020-21, a field experiment was undertaken at Regional Research Station, Tamil Nadu Agricultural University, Vridhachalam to investigate the effect of integrated nutrient management on the groundnut-blackgram cropping sequence. Four nutrient combinations for groundnut were tested in a randomized block design and the residual effect on productivity of succeeding blackgram was investigated using four fertilizer levels in a split plot design.

The application of 125% RDF + FYM @ 12.5 t ha^-1 to groundnut increased growth, yield, quality, economics and soil properties, while the residual effect to succeeding blackgram resulted in significantly higher blackgram seed yield and other important parameters, which was followed by the application of 75% RDF. Among the various levels of fertilizers applied to blackgram, 75% RDF produced the highest blackgram seed yield, economics and soil characteristics compared to the other three levels.