MAJOR NUTRIENT FLUXES AND WATER USE EFFICIENCY OF WINTER VEGETABLES UNDER PERI-URBAN FARMING OF NORTH-WESTERN PUNJAB, PAKISTAN

Major nutrient fluxes in urban and peri-urban agriculture (UPA) under semi-arid conditions in north-west of Pakistan are not fully known. To envisage it, a field study was carried out in Faisalabad, Pakistan. Three fertilizers treatments (an unfertilized Control, F0; farm yard manure, FYM (F1) at 14.2 t dry matter (DM) ha(-1) containing 108 kg Nitrogen (N), 27kg Phosphorus (P) and a mineral fertilizer treatment (F2) containing the same amount of N and P as in F1 were established during 2011-12. Fertilizer treatments were factorally combined with two irrigation levels i.e. RI; recommended irrigation when irrigation was applied weekly and HRI; half than recommended irrigation where irrigation was applied fortnightly. Subplots randomized within each main plot were assigned to either of the two vegetable species pea (Pisum sativum L.), cauliflower (Brassica oleracea L.). Highest crop dry matter yields (p>0.05) were recorded for pea (12 t ha-1) under F2 and lowest for cauliflower in RI (6.2 t ha(-1)) under F1 treatment, respectively. Dry matter yields of both crops were reduced to 11-18% by reducing applying half of the HRI presumably due to water stress. Contrarily, water use efficiencies of both crops were significantly (32-36%) higher under HRI treatment than under RI. Apparent nutrient use efficiencies for C, N, P and K varied widely ranged from 27-34%. However partial nutrient balances of major nutrients specially for K, remained negative. These results indicate large K mining in the soil which required proper balancing.