Study of Rice and Soybean-Corn Rotation with Organic Fertilizer Application in Blora, Central Java

Abstract

The use of chemical fertilizer since several decades ago potentially reduce soil fertility and crop yield. Organic farming system can be applied to solve this problem through the use of a variety of organic fertilizers. Organic fertilizer application is useful because it is capable to improve the physical, biological, and chemical soil fertility and produce safe-consumed food and safe for environment. Only a few number of farmers in Blora, Central Java use organic fertilizer as the source of plant nutrient because it is considered less efficient in terms of the amount of which is given. Most of the farmers in Blora apply rice-corn cropping pattern every year. Crop rotation is highly recommended to be applied to break down life chain cycle of the pest and to improve the soil fertility. The study consisted of organic rice experiment in the first cropping season (January-April 2012) and organic soybean and corn experiment in the second one (May-September 2012). The organic fertilizers were used in the study tailored to the types of organic fertilizer which available in the experiment site. Organic fertilizer application in the second cropping season resulted in the higher nutrient content of available-P and Ca, and better plant growth and yield than those with organic fertilizer application in the first one. Nutrient immobilization was predicted still occured during the first cropping season, so that resulted in the lower nutrient content and plant performance than those in the second one. This research was not fully meet the criteria of organic farming especially for the experiment site requirements, but it was an initiation to meet the qualification of organic farming system. The organic rice experiment in the first cropping season showed that the application of cow manure did not significantly increase the rice yield, but there was a trend that the application of 10 tons cow manure ha-1 with square spacing 20 cm x 20 cm or application of 3 tons corn biomass ha-1 + 7.5 tons cow manure ha-1 with double-row spacing 40 cm x 25 cm x 15 cm resulted in the higher rice yield than with other treatments. The organic soybean experiment in the second cropping season showed that the application of 7.5 tons of cow manure or application of 7.5 tons sheep manure ha-1 were more efficient in producing organic soybean seed than other treatments. After organic rice cultivation in the first cropping season, the organic corn experiment in the second one showed that the application of 11.25 tons cow manure ha-1 or application of 11.25 tons sheep manure ha-1 were more efficient in producing organic corn seed than other treatments. Based on the yield and the value of R/C ratio, organic rice-soybean cropping pattern was more profitable than organic rice-corn cropping pattern.