Vanishing Process of 15-year fertilization on the Paddy Field

大米的简历。1993 - 2008年15年间，在由火山灰土旱田改造而成的水田中，采用9种不同的施肥制度（2块不施肥，7块不施肥，化学肥料和有机肥混合施用）无害化栽培Mineasashi。2009年至2013年，这9个地块的施肥制度在不施肥的情况下发生了变化。观察和分析了施肥对水稻生长、产量和糙米蛋白质含量的影响。施用化肥的地块分蘖出苗率较高，因而水稻产量和蛋白质含量高于不施用化肥的地块。2009 ~ 2013年，9块田不施肥的平均产量基本持平。从这些结果来看，15年间连续施用化肥的效果，无论是化学的还是有机的，在不施用化肥的第一年完全消失。

Rice cv. Mineasashi was cultivated with no pesticides in the following nine different fertilization regimes as no fertilizer in two plots and in 7 plots fertilized by chemical fertilizers, and organic fertilizer during 15 years from 1993 to 2008 in the paddy field converted from volcanic ash soil upland field. In 2009, fertilization regimes in these nine plots changed under no fertilizer up to 2013.The effects of applying fertilizers on rice growth, rice yield, and protein content of brown rice were observed and analyzed. Plots with fertilizers had so more tiller emergence that more rice yield and more protein content than plots with no fertilizer. However, mean rice yield with no fertilizer from 2009 to2013 in 9 plot was almost the same. Judging from these results, the effect of continuous application of fertilizers during 15 years, regardless of chemical or organic, completely vanished in the first year when no application of fertilizer was started.