Effect of basal application methods on weed growth and nutrient uptake in lysimeter paddy field
2006
Kaneda, Y.(Akita Prefectural Univ. (Japan). Faculty of Bioresource Sciences) | ; Sasaki, K. | ; Sato, T. | ; Murai, A. | ; Sugawara, S. | ; Sato, A.
We investigated the effect of the basal application method, a single application of fertilizer in a nursery box (SAF) and the whole layer application of fertilizer (WAF) on weed growth and nutrient uptake in a lysimeter paddy field of gray lowland soil. The amount of ammonium nitrogen in the plow layer of the interrow space was higher in the WAF plot than in the SAF plot. The SAF restrained the dry matter of weeds as compared with the WAF. This tendency was more pronounced year by year. The dry matter of weeds in the SAF plot was lower than that of the WAF plot in the 3rd year of rotational paddy field. Barnyard grass (Echinochloa oryzicola Vasing.) accounted for over 98% of the WAF plot and about 77% of the SAF plot in terms of dry matter. The tiller number of rice was the lowest under the unweeded control in the WAF plot. The relative light intensity was lower at all heights under the unweeded control in the WAF plot compared with that under hand weeding. The amount of nutrient uptake of rice under the unweeded control in the WAF plot was greatly restrained compared with that under the unweeded control in the SAF plot. The amount of nutrient uptake of weeds was lower in the SAF plot than in the WAF plot. Barnyard grass (Echinochloa oryzicola Vasing.) accounted for most of the nutrient uptake of the WAF plot. The rice yield in the unweeded WAF was significantly influenced by weeds, and was 16% of that of hand weeding due to the decrease in number of grains per unit area and thousand grain weight. The rice yield in the unweeded SAF plot was 83% of that of hand weeding. The rate of grain yield (unweeded control/hand weeding) was higher in the SAF plot than in the WAF plot. These results suggested that a single application of fertilizer in a nursery box in a rotational paddy field decreased weed growth and maintained rice yield.
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