No abstract

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 (CT 1 ) and CT 1 + application of ZnSO 4 (CT 2 ) 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: CT 2 > CT 1 > 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 (À39.4 kg ha À1 y À1 ). In spite of fertilizer-K application in the intervention plots, K balance was negative (À14.4 to À19.5 kg ha À1 y À1 ). 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 À1 y À1 .

The main objective of the study was to assess the soil nutrient status of two cotton (Gossypium hirsutum L.) cultivation systems (organic and modern method of cultivation) established in 1994. In general, the data indicate a depletion of the nutrient status with depth (0-0.1, 0.1-0.2, 0.2-0.3, 0.3-0.6, and 0.6-0.9 m). There was a significant build up of organic carbon (C) and nutrients, except iron (Fe) and magnesium (Mg), in the organic cultivation system (OCS) compared to the modern method of cultivation (MMC). Most of the accumulation was noticed in the top 0-0.3 m. The concentration of the mobile nutrient NO À 3 was significantly greater in the surface as well as in the deeper layers of the OCS plots than the MMC plots. Extractable P ORDER REPRINTS was 3.8-fold greater in the OCS than MMC plot in the top 0.1 m soil layer. At 0.3-0.6 m soil depth, it was 3-fold greater. Other immobile nutrients such as zinc (Zn), Fe, manganese (Mn), and copper (Cu) were also significantly greater in the 0.3-0.6 m depth in the OCS plots compared to the MMC plots possibly due to movement of enriched topsoil through the cracks following cultivations.