Evaluation of cropping sequences of hybrid vegetables for N fertilizer recovery efficiency and utilization of residues using ~(15)N-enriched urea

摘要

In intensive cultivation of vegetables, several cropping sequences in each region are popular depending on market needs and profit. Since different vegetable crops differ in their nutrient needs, relative dependence on soil vis-a-vis fertilizer sourceof nutrients and fertilizer recovery efficiency, there is scope to evaluate different sequences of vegetable crops for high nutrient use efficiency. Stable isotope ~(15)N is highly useful to investigate N use efficiency by crops grown in different cropping systems (Bosshead et al. 2009). Since hybrid vegetables need higher fertilizer dosages, there is scope to identify the most nutrient efficient sequence for cost effectiveness and eco-safety. For the sake of such an evaluation the possible sequences of okra (Abelmoschus esculentus)-tomato (Lycopersicon esculentum)-cabbage (Brassica oleracea var. capitata) was considered. The crops of the sequence were chosen on area under these crops, their productivity, market arrivals in Bangalore (NHB 2010) and their popularity. The experiment was raised during 2003-04 on a sandy loam (typic Haplustalf) soil having a pH. of 5.9, organic carbon of 0.30%, cation exchange capacity of 8.7 cmol (p+)/kg and available N of 246 kg/ha. Six possible cropping sequences as listed in Tables 1 and 2 were raised in 3 series. In the first series of each sequence, the first crop, in the second series of the same sequence, the second crop and in the third series of the same series, the third crop received ~(15)N labeled fertilizer. For instance, in the first sequence: okra-tomato-cabbage, okra crop received ~(15)N labeled fertilizer in the first series. The second crop, tomato, and the third crop, cabbage, in the same sequence, received ~(15)N labeled