Evaluation of nutrient availability of sandy soil in Northeast Thailand with reference to growth, yield and nutrient uptake by maize.

摘要

A field experiment was conducted on a sandy soil of the Khon Kaen University in northeast Thailand to: (i) examine the relationship between nutrient content in soil and growth, yield and nutrient uptake by maize for a set of NPK fertilizer applications; (ii) evaluate the effect of those nutrients on the growth and yield of maize for the identification of limiting factors; and (iii) propose a rational management practices for the agricultural system established on the marginal sandy soil. Six treatments were applied: NPK (100 kg/ha), PK, NK, NP, control, and NPK+manure. Soil (Typic Ustipsamments) samples were collected from the plough layer (0-20 cm) as composite samples and from several horizons up to 125 cm depth. The available and total contents of NPK were determined. Harvested plants were measured for dry weight, yield and NPK contents. The amounts of available N, P and K within 1 m of soil were 47, 261 and 256 kg/ha, respectively. Approximately 37% of available N and 50% of available P were stored within the surface 20 cm, where more than 80% of the roots distributed. Aboveground biomass in the PK, NK, NP and NPK treatments were 4, 25, 79 and 98% higher than the control (3.71 t/ha), respectively, indicating that N was the most dominant limiting factor, followed by P and K.