Response of fertilizers in maize (Zea mays)-wheat (Triticum aestivum)-cowpea (Vigna unguiculata) cropping system

A field experiment was conducted for 3 years on a Typic Ustochrept of Delhi under the All-India Co-ordinated Research Project on Long-Term Fertilizer Experiments with different fertilizer combinations following maize (Zea may s L.)-wheat (Triticum aestivum L. emend. Fiori & Paol.)- cowpea [Vigna ungu iculata (L.) Walp.] (fodder) sequence. Soil-test based 100% optimum recomme nded dose of 120,60 and 40 kg/ha N, P2O5 and K2O for wheat and maize and 20 , 40 and 20 kg/ha for cowpea showed significantly higher grain and straw or stover yields of both grain crops as well as the dry-fodder yield of cowpe a during ail the 3 years than unfertilized plots. Use of N or NP alone yiel ded quite low, comparable to 50% of the recommended dose. NPK + FYM gave as high yield of maize as the superoptimal dose of 150% and consistently high er yield of wheat grain. Use of S or Zn or hand-weeding showed no yield adv antage. The FYM treatment maintained high level of fodder yield of cowpea.