Amendments to Improve Soil Fertility and Increasing Maize (ZEA MAIZE) YIELD in MID Country Sri Lanka.

Sri Lankan soils are generally low in soil fertility and high inputs are often needed for crop production. This study evaluated beneficial management practices to overcome the soil physical and chemical limitations in growing maize (Zea maize). The experiment was conducted in the Mid Country Intermediate Zone (IM3c) with Reddish Brown Latosolic soils (Rhodudalfs). A composite soil sample (0-20 cm depth) was collected and analyzed for soil fertility parameters and available nutrients. A site-specific fertilizer (SF) recommendation was formulated using the modified missing element technique. Four treatments, (1) SF, (2) biochar applied at 0.5% by weight with SF (BC+SF), (3) incubated cattle manure and saw dust applied at 1% by weight with SF (CS+SF,) and (4) un-amended control (C) were initially tested at the greenhouse for 72 days and later in field for a complete growing season of maize. Soil was slightly acidic, non-saline, sandy loam in texture with a moderate cation exchange capacity (13.5 cmol₊/kg) and low organic matter content (1.3%). According to initial analysis soils was deficient in available N, P, K, S, Ca, Zn, Cu, Mn and sufficient in Mg and Fe. In the greenhouse, plant dry weight increased significantly with the addition of amendments i.e., fertilizers alone (SF), or with biochar (BC+SF) and cattle manure- sawdust (CS+SF). Plant dry weights and length of cob significantly increased in all treatments with fertilizer compared with the control but no significant difference was observed between amendment treatments and the SF only treatment. Significantly higher grain yield (6825 kg/ha) was observed for the BC+SF treatment than other treatments. Seed number per cob was significantly greater for the biochar treatment. Complete nutrient package developed based on the soil analysis significantly increased the plant growth. High C:N ratio of amendments did not limit the available nutrients in the greenhouse or in the field. No significant difference was observed for soil pH with the addition of amendments. The results of the field experiment suggest that biochar with adequate nutrients effectively improved soil constraints in the RBL soil and significantly increased the maize yield.

HETC/QIG/Window3/PGIA grant is acknowledged for the financial assistance.