Maize yield and soil properties as influenced by integrated use of organic, inorganic and bio-fertilizers in a low fertility soil

A field experiment was conducted to investigate the effect of integrated use of organic and inorganic fertilizers in a low fertility soil at Agricultural Research Institute, Tarnab, Peshawar. The experiment comprised of ten treatments arranged in a RCB design with three replications. The treatments were control, 50% of recommended NPK, 100% of recommended NPK and then each NPK treatment combined either with farm yard manure (FYM), humic acid or Azotobacter inoculum alone and in combinations. The results showed that combining organic sources with 50% of recommended NPK fertilizers produced the highest grain and biological yields of maize over the 50% NPK treatment and were statistically at par with those receiving 100% NPK fertilizers. Almost the same trend was observed for leaf area index and grain harvest index. Moreover, the net return was also greatest when organic sources were combined with 50% of recommended NPK fertilizers. Among organic sources, the effect of FYM was more prominent. The effect of FYM was further enhanced when Azotobacter incoculum was also added. However, the effect of humic acid was not evident neither with 100% nor with 50% of recommended NPK fertilizers. The soil analysis after crop harvest revealed that soil organic matter, total N, extractable P and K, EC and total soluble salts were all greatest for treatment receiving organic sources with 50% of recommended NPK fertilizers. Soil pH on the other hand was lowest in the corresponding treatments. These results thus suggest that integrating organic sources with 50% of recommended NPK fertilizers are appropriate for sustainable crop production on a low fertility soil.