Title : Thirty four years of Long-term Integrated Nutrient Management on soil nutrient balance and productivity of rainfed Groundnut (Arachis hypogea) in an Alfisols in Arid region of Andhra Pradesh, India
The soil nutrient dynamics and groundnut pod yields studied in the ongoing long-term integrated nutrient management for groundnut experiment initiated during rainy (kharif) season 1985 at Agricultural Research Station, Anantapur, in an alfisols in Arid region of Andhra Pradesh, India, under All India Coordinated Research Project for Dryland Agriculture, in mono cropping system of groundnut (Arachis hypogea), with ten treatments comprising of inorganics with and without recyclable farm wastes viz. FYM, groundnut shells and replicated three times in RBD. Every year, soil samples from all the treatments collected at 0-15 cm depth. The lowest groundnut pod yield was recorded in control treatment (164 kg ha-1) in 2014, while the maximum was in INM treatment which received HRFD + FYM @ 4 Mg ha-1(2202 kg ha-1) in 2017. Thirty four years’ average pod yield of groundnut, the treatment with integration of both organics (FYM @ 4 Mg ha-1) and inorganics (Half Rec. Ferti. Dose @ 10-20-20 N-P2O5-K2O kg ha-1) recorded 968 kg ha-1over Full Rec. Dose @20-40-40 N-P2O5-K2O kg ha-1 (943 kg ha-1). Groundnut being a leguminous crop and the economic pod is in the soil zone, the impact of chemical fertilizers on productivity is limited compared to the organic manure as it provides congenial smooth soil for peg penetration and pod development besides supplying nutrients in a balanced manner. The yields of groundnut over years maintained consistently with integrated sources, while, declining trend was observed with absolute control. Groundnut responds positively in terms of SYI to the organic sources in long run whereas negative trend with inorganic fertilizers. INM treatment with application of FYM @ 4 t ha-1 +50 % NPK recorded higher SYI (0.234) followed by 100 % NPK (0.223) compared to absolute control (0.127). Higher removal of N, P and K (3018, 270 and 588 kg ha-1) was observed in 50 % RDF + 4 Mg ha-1 FYM followed by 100 % RDF (2834, 255 and 554 kg ha-1) and100 % Organics (2779, 248 and 544 kg ha-1). In control, negative balance of N (-2020 kg ha-1), P (-151 kg ha-1) and K (-233 kg ha-1) were observed. The highest positive balance of N (409 kg ha-1) in 50 % RDF + 4 Mg ha-1 FYM, P (1125 kg ha-1) in 100 % RDF treatment and K (1802 kg ha-1) in 50 % RDF + 4 Mg ha-1 GNS treatment were observed after 34 years. The treatment with half the recommended dose of fertilizer (10:20:20 kg N, P2O5, K2O) along with FYM @ 4 Mg ha-1 recorded higher Soil Organic carbon stocks (13.42 Mg ha-1) and Microbial biomass carbon (1035 µg g-1) at surface soil depth. So keeping in view of soil nutrient status, the treatment Half Recommended Fertilizer Dose (10-20-20 N, P2O5, K2O kg ha-1) along with Farm Yard Manure @ 4 Mg ha-1 is giving at par yields compared to full recommended dose of fertilizers which not only giving sustainable yields but also enhancing the soil health.