长期施肥对红壤双季稻冬闲田春季杂草群落的影响

Effects of long-term fertilization on spring season weed community in winter fallow paddy field in red soil area under double-rice cropping system

利用始于1982年的红壤双季稻田长期施肥定位试验,于2012年采用田间调查法研究了在无机肥(化肥NPK)与有机肥(M)氮磷钾养分等量条件下,长期施用有机肥、无机化肥和有机肥无机肥配施模式下红壤双季稻冬闲田春季杂草生物量及群落密度和群落多样性的变化。结果表明:有机肥无机肥配施改变了优势杂草种类,增加了杂草总密度和总生物量。化肥氮钾配施有机肥(NKM)处理的杂草种类数量最多,化肥氮磷配施有机肥(NPM)处理的最少。施肥处理中,M处理的杂草群落多样性指数、均匀度指数和优势度指数均最高,分别为1.118 6、0.732 3和0.629 7;其杂草总密度最低,为297.0株?0.25m?2。NPK处理的杂草总生物量最低,为58.0 g?0.25m?2。NPM处理的杂草群落多样性指数值、均匀度及优势度指数值均显著低于其他处理;其杂草总密度和杂草总生物量均最高,分别为539.7株?0.25m?2和109.5 g?0.25m?2;其优势杂草日本看麦娘的密度为428.0株?0.25m?2,相对密度为79.31%,明显高于其他处理优势杂草的密度和相对密度。春季杂草总干物质量与土壤碱解氮正相关(相关系数为0.703),与土壤p H负相关(相关系数为0.697),相关性不显著;与土壤有效磷显著正相关(相关系数为0.758*)。长期不同施肥模式下红壤稻田磷素是导致田间春季杂草群落特征变化的主要因素,通过改变土壤有效磷和碱解氮含量及土壤p H,能有效调控红壤双季稻冬闲田春季杂草生物量及群落密度和生物多样性。

An investigation in winter fallow field of double-rice cropping system in the red soil area was carried out in 2012 in a long-term fertilization experiment（started in 1982） site in Hengyang Red Soil Experiment Station of Chinese Academy of Agricultural Sciences to study the species, biomass and biodiversity of weed communities during spring season. The investigated long-term fertilization experiment included five fertilization treatments of application of organic fertilizer, chemical fertilizer and combined application of organic and inorganic fertilizers with the same rates of nitrogen（N）, phosphorus（P） and potassium（K） in both the organic and chemical fertilizers, which were no fertilizer（CK）, organic fertilizer（composted cattle manure, M）, combined application of P and K inorganic fertilizer and organic fertilizer（PKM）, application of inorganic N, P, and K fertilizer（NPK）, combined application of N, K inorganic fertilizer and organic fertilizer（NKM）, combined application of N, P inorganic fertilizer and organic fertilizer（NPM）, and combined application of N, P, K inorganicfertilizer and organic fertilizer（NPKM）. The results showed that the dominant weed species changed and the total density and total biomass of weed communities increased under combined application of organic and inorganic fertilizers. NKM treatment had the largest number of weed species, while the least weed species number was under NPM treatment. Species diversity index（1.118 6）, evenness index（0.732 3） and dominance index（0.629 7） of weed communities under M treatment were larger than those under the other treatments. However, M treatment had the lowest total weed density（297.0 plant·0.25m-2）. Also NPK treatment had the lowest total weed biomass（58.0 g·0.25m-2）. Compared with other treatments, NPM treatment significantly decreased diversity, evenness and dominance indexes of weed communities, and had the highest total weed density（539.7 plant·0.25m-2） and total weed biomass（109-5 g·0.25m-2）, respectively. Alopecurus japonicas was the dominant weed species, and had weed density of 428.0 plant·0.25m-2 and relative weed density of 79.31% under NPM treatment, which were significantly higher than those of dominant weeds under other treatments. It was noted in this study that total dry biomass of weeds was positively correlated with content of soil alkali-hydrolyzable N（r = 0.703）, negatively correlated with soil p H（r = –0.697）, and significantly positively correlated with soil available P content（r = 0.758）. Thus soil P was considered as the main factor responsible for the characteristic changes in weed communities under long-term fertilization modes. The proper regulation of soil p H and contents of soil alkali-hydrolyzable N, soil available P and especially soil available P through different long-term fertilization schemes could effectively managed biomass, density, and biodiversity of weed communities during spring season in winter fallow paddy field in the red soil area.