Organic Versus Inorganic Management on the Yield and Soil Fertility of Irrigated Lowland Rice

Abstract

Organic farming is being promoted by advocates to sustain and improve soil fertility compared to conventional farming that uses inorganic fertilizers and pesticides. The study was conducted to determine the effect of pesticide and fertilizer management practices on grain and straw yields, yield components, and soil fertility of irrigated lowland rice. The experiment was conducted for three consecutive seasons (2009-2010) at Los Baños, Laguna, Philippines. It was laid out in a Split Plot design consisting of two main plots: with pesticides (M1) and without pesticides (M2), and four subplots: control (T1), organic fertilizer only (T2), inorganic fertilizer only (T3), and one-half (½) rate of inorganic plus ½ rate of organic fertilizers (T4), with four replications. Generally, pesticide application did not affect the yield and yield components. Plots applied with inorganic and one-half rate of combined organic and inorganic fertilizers had significantly higher grain yields than the control and organic only fertilizer treatments. Application of limiting nutrients through inorganic fertilizers helps to correct most of soil deficiencies such as phosphorus and sulfur compared to the use of organic fertilizer alone. Combining organic materials such as compost and rice straw with inorganic fertilizers at one-half rates is an effective strategy to attain yields comparable to pure inorganic application to sustain soil fertility.