Author : Pheap Sambo

Summary : Mineralization of nutrients from organic materials is vital for optimum plant growth and development. Various methods have been used to evaluate the mineralization rate of different organic material and substrates. Of these, carbon dioxide evolution is a reliable method to estimate mineralization rate. Four different substrates were utilized for the research; dry chicken manure (CM), Azolla (AZ), coconut coir dust (CCD), and Gliricida sepium leaves (GS). The effect of the combination of these organic materials with additional nutrients sources (Simple Nutrient Addition Program [SNAP] solution for the incubation study and recommended rate [RR] for pot experiment) on their rates of mineralization were determined, as well as corn growth. The results of the incubation showed significant differences in the amounts of CO2 evolved from the substrates. The evolution of CO2 from the substrates was stimulated by SNAP solution. Among all treatments, GS + SNAP yielded the highest result while CCD gave the lowest amount which was almost as low a as the control. Over eight weeks of incubation, nitrogen mineralized to about fifty percent (50%) during the first week in all treatments. By the end of the incubation period, GS + SNAP produced the highest amount of mineralized nitrogen (9.40 mg kg-1 soil) while CCD had lowest N mineralized (8.03 mg kg -1) compared to other treatments with organic materials and SNAP. Results of soil analysis indicated that GS + RR (90-30-30) produced more nutrients in the soil compared to the rest of the treatments, as well as other organic materials with RR. Gliricidia sepium with recommended fertilizer rate had the highest nitrogen at both 48 and 90 DAS (1.17 g, 1.23 g) followed by AZ + RR (0.77 g, 0.90 G) and other organic materials with RR. Moreover, GS + RR produced 150.68 g of biomass, followed by CCD + RR (140.13 g), CM + RR (132.84 g) and A Z + RR (132.25 g), respectively. Using oil organic materials such as Gliricidia sepium leaves would quickly provide the soil with more mineralized nutrients which are available for plant growth and development, resulting in better biomass production of corn plants. It is god practice to use pure organic materials, especially Gliricidia sepium for small scale or household use. For larger production, the combination of organic materials and manufactured fertilizers would help to maintain matter and obtain good crop production.