RESTORING CROP PRODUCTIVITY OF ERODED LANDS THROUGH INTEGRATED PLANT NUTRIENT MANAGEMENT (IPNM) FOR SUSTAINED PRODUCTION

Crop productivity of eroded lands is very poor due to removal of top fertile soil losing organic matter and plant nutrients. Crop productivity of such marginal lands needs to be restored in order to meet the food requirements of increasing population. Therefore field experiments were conducted at Thana, Malakand; Kabal and Matta, Swat, North West Frontier Province (NWFP) of Pakistan for three years during 2004 to 2005- 2006 to study the effect of inorganic fertilizers alone and in combination with farm yard manure (FYM) under two cropping systems i.e. wheat-mungbean-wheat and wheat-maize-wheat on the yield of wheat. The fertilizer treatments consisted of farmer's practice: Tl (60-45-0 kg N-P2 05-K20 ha-1), balanced rate of inorganic fertilizers: T2 (120-90-60-5 kg N-P205-K20-Zn ha-1), and combined application of inorganic and organic fertilizers: T3 (60-90-60-5 kg N-P205-K20-Zn ha-I + 20 t FYM ha-1) for wheat crop. Maize and mungbean crops were grown in the respective treatments after wheat crop during summer 2004 and 2005. Maize crop received the same treatments after wheat in the same plots except FYM in T3. In case of mungbean, no nitrogen and FYM was applied in all the three treatments. Experiments were laid out in a RCB split plot arrangement with cropping systems in the main plots and fertilizer treatments in the subplots. Three replications were used in each experiment. The results showed that the combined application of FYM with NPKZn (T3) increased the grain yield of wheat significantly over the other two treatments with an increase of 30-61 % over TI and 3 to 18 % over T2 While T2 increased the yields significantly over TI with an increase of about 14 to 45 %. Similar trends were observed for straw yields. Among the two cropping system, mungbean Wheat system increased the Wheat yields significantly over maize-wheat based on the pooled data of the two years (2004-2005 and 2005-2006) with an increase of 14 %. Yields during 2005-2006 were higher than the ones during 2004-2005 based on the pooled data of the sites due to more rainfall during the former year than the latter one. Based on the pooled data of three sites, there was variation in crop yield among various sites. The highest yields were recorded at Matta followed by Thana and Kabal Economics of fertilizer use for wheat showed that the highest net returns were recorded in case of T3 followed by T2. Net returns from mungbean-wheat system were either comparable with maize-wheat or greater than the latter. Similar to wheat, summer crops of maize and mungbean responded to combined application of organic and inorganic fertilizers as T 3 increased the yields of these crops significantly over T2 and T1. As regards soil properties, T3 improved soil physical properties (bulk density, total porosity and available water capacity), chemical properties (pH and organic matter), microbiological properties (respiration and cumulative respiration, mineralizable-C and -N, mineral-N, soil microbial biomass-C and-N and bacterial and fungal population) and soil fertility status (AB-DTPA ext. P, K, Zn, Cu, Fe and Mn) over a period of time. These soil properties were also improved in wheat-mungbean-wheat cropping system. It can be concluded that application of balanced rate of fertilizers in combination with organic manure would improve organic matter and soil fertility in surface layer, improve the soil physical environment, soil microbiological properties and restore crop productivity, under wheat-mungbean-wheat system for sustainable agriculture as compared with wheat-maize -wheat system. Thus crop productivity of eroded lands can be improved on sustainable basis by adopting integrated plant nutrient management.