Effects of Foliar and Soil Applied Fertilizers on Cambodian Rice

Abstract

Cambodian soils used for lowland rice cultivation are low in available nitrogen (N), phosphorus (P) and potassium (K), and have low organic matter content and low cation-exchange capacity. Soil application of fertilizersis mainly used for rice production in the country. Foliar fertilization is an efficient way to enhance rice growth and production, but is unknown for Cambodian rice and conditions. We aim to determine the effects of foliar plus soilapplied fertilizers on growth and yield of Senpidao rice variety (Oryza sativa L.). The experiment with randomised-completed block design was conducted with four replications for five different treatments and one control group in plots of 3m ´ 4m. Soil of the experimental plot was classified as Brown hydromorphics or Toul Samroung soils, which 100 kg N, 52 kg P₂O₅, 00 kg K₂O ha^-1 are recommended for rice cultivation.In treatment 1 (T1), foliar fertilizer (FF) was solely applied; soil applied fertilizers (i.e. Urea, DAP-diammonium phosphate) were used to meet ¼, ½ and ¾ recommonded rate (RR) and suplemented with FF for T2, T3 and T4, respwctively; T5, full RR dose with no FF and T0, untreated control.In each plot, 19 days old rice seedlings were directly transplanted2-3 seedlings per hill, and 20cm ´ 20cm plant spacing. Urea and DAP were applied to soil at three stages (i.e. transplanting date, 25 DAT-days after transplanting, PI-panicle initiation). Foliar fertilizer was well dissolved into water (1 kg ha^-1) and sprayed on rice leaves twice, at 25 DAT and PI stage. We found all response variables generally increased with the amount of soil applied fertilizersin T2, T3 and T4, whereas ones in T4 and T5 were not significantlydifferent.Tiller numbers, panicle numbers per tiller, 1,000-grain weight and grain yield in T1 were significantly greater than T0.The findings suggest that improved grain yield (as measured by increased tiller numbers, panicle numbers and decreased panicle sterility) was due to foliar fertilization. The results of this study indicate that one-fourth of the soil-applied fertilizers could be substituted by foliar fertilization in rice cultivation in Cambodia.