ORGANIC WASTES AS ALTERNATIVE TO INORGANIC FERTILIZERS IN CROP CULTIVATION

Abstract

The use of organic wastes (OW) as alternative to chemical fertilizers not only results in an economic benefit to the small-scale farmer but it also reduces pollution due to reduced nutrient run-off, and N leaching. Almond and pistachio N, P and K requirements can be satisfied by adding OW. With trees, as is the case of almond and pistachio, it is better to fertilize smaller doses more frequently. This increases percentage of fertilizer uptake while reducing the risk of nutrient leaching. Accordingly, the use of OW as alternative to inorganic fertilizers is very convenient since they slowly release significant amounts of N and P. In this work, the effect on crop yield and soil quality of two OW at three N rates in comparison with the use of inorganic fertilization was evaluated. For practical reasons barley and ryegrass were used as test plants but obtained results can be extended to almond and pistachio tree cultivation or any other crop. OW increased crop yields with respect to the control at the three assayed rates, and led to similar ryegrass yields and slightly lower barley yields than inorganically fertilized soils, indicating that the use of OW can be a suitable alternative to inorganic fertilizers. Both OW enriched soil in available K, Mg, Mn, S and ammonium and had a stimulant effect on microbial growth and activity, OW treated soils showing higher microbial biomass C and basal respiration than control after crops. Results showed that land application of OW as fertilizers not only provides essential nutrients to plants but also improves soil quality.