Nutrient uptake and balance of cotton plus pigeonpea strip intercropping on rainfed vertisols of central india

Nutrient uptake and balance of the cotton (Gossypium hirsutum L.) + pigeonpea (Cajanus cajan(L.) Millsp.), a traditional strip intercropping system practiced on the rainfed Vertisols of central India is not known to us. On-farm participatory trials were conducted on 10 farmer fields, five each on medium deep (MDS) and deep soils (DS) of Nagpur, central India to determine the effect of technological interventions on N, P and K uptake of cotton and pigeonpea. The nutrient balance was also quantified as a difference of nutrient inputs and removal. Nutrients accumulated by the crops (grain, stalk and leaves) and weeds removed off the field by hand weeding were considered as nutrient removal, while fertilizer was considered as nutrient input. The interventions included application of recommended dose of fertilizer (RDF), RDF + conservation tillage with in situ green manure (CT1) and CT1 + application of ZnSO4 (CT2) and compared with farmers' practice (FP). Nutrient uptake, in general, was higher on DS than on MDS. Among the interventions, N, P and K uptake of cotton and pigeonpea followed the order: CT2 > CT1 > RDF > FP. Mean N and P balance was positive in all the treatments. The balance may become negative if nutrient losses are accounted. A negative K balance was observed in all the treatments and the magnitude was the greatest for the FP plots (-39.4 kg ha(-1) y(-1)). In spite of fertilizer-K application in the intervention plots, K balance was negative (-14.4 to -19.5 kg ha(-1) y(-1)). By way of leaf and fruit drop, cotton and pigeonpea litter recycled 12.2 kg N, 1.7 kg P and 6.7 kg K ha(-1) y(-1).