|Effect of different long-term fertilization treatments on the spring weed community in winter fallow paddy field in yellow soil area under the single-rice cropping system
|英文关键词: long-term fertilization, yellow soil, single-rice cropping system, winter fallow paddy field, weed community, community diversity
| 为探讨长期不同施肥模式下杂草群落变化及其与土壤养分相关性，依托一项连续24年长期施肥试验，采用田间调查法，对不平衡施肥[氮磷肥（NP）、磷钾肥（PK）、氮钾肥（NK）]、常量化肥（NPK）、单施有机肥（M）、1/2有机肥替代化肥（1/2MNP）、不施肥（CK）模式下黄壤单季稻冬闲田春季杂草群落变化及其与土壤养分相关性进行研究。结果表明，长期不同施肥模式下春季杂草密度、生物量、群落多样性等均发生变化。M处理下土壤养分均较高，杂草群落总密度1 208.44株·m-2、总生物量1 071.24 g·m-2，均为最高，与CK处理相比，春季杂草总密度增加37.74%、总生物量增加179.58%，说明单施有机肥可提升土壤养分，促进春季杂草生长。不同处理对杂草群落影响存在差异：M处理下棒头草（Polypogon fugax）等未发生；长期施用无机化肥处理早熟禾（Poa annua）发生密度（0~4.89株·m-2）较低；缺磷处理下日本看麦娘（Alopecurus japonicus）发生密度（36.00株·m-2）最低。同时，缺氮导致杂草群落多样性指数增加、优势度指数降低，群落结构相对复杂；缺磷则反之。研究表明，全氮、碱解氮和全磷是影响杂草密度的关键因子，生产上可通过合理施肥控制田间杂草发生，稳定土壤肥力及物种多样性，促进农业生态系统发挥出最大生态效应。
| To understand the changes of spring weed community diversity and the correlation with soil nutrients under different long-term fertilization models, a field investigation based on a continuous 24-year long-term fertilization test was conducted in winter fallow paddy field in the yellow soil area of Guizhou Province, China, under a single-rice cropping system. The different treatments were unbalanced fertilization（NP, PK, NK）, constant fertilizer（NPK）, single organic fertilizer（M）, 1/2 organic fertilizer instead of chemical fertilizer（1/2 MNP）, and no fertilization（CK）. The results showed that spring weed density, biomass, and community diversity all changed under the conditions of the different long-term fertilization modes. Under the M treatment, soil nutrients were all higher, and the total density and total biomass of the weed community were both highest（1 208.44 plants·m-2 and 1 071.24 g·m-2, respectively）. Compared with the CK treatment, the total density of weeds was 37.74% higher, and the total biomass was 179.58% higher. These results indicated that the M treatment improves soil nutrients and increases weed density and biomass in spring. The different treatments had different effects on the weed community. Under the long-term single application of organic fertilizer（M）, Polypogon fugax did not occur. Under the condition of long-term use of inorganic fertilizer, the density of Poa annua was lowest, from 0 – 4.89 plants ·m-2, and under phosphorus deficiency,Alopecurus japonicus was suppressed, showing its lowest density（36.00 plants·m-2）. These results indicated that the different long-term fertilization treatments could inhibit the occurrence of different weeds. In terms of weed biodiversity, the weed community diversity index increased, the dominance index decreased, and the weed community structure was relatively complex under the condition of the nitrogen deficiency. On the contrary, the diversity index decreased, the dominance index increased, and the community structure was relatively simple under phosphorus deficiency. Our results indicated that total nitrogen, alkaline nitrogen, and total phosphorus were the key factors affecting weed density. Hence, reasonable fertilization can control the damage caused by weeds in the field and stabilize soil fertility and species diversity. Moreover, it can promote the agricultural ecosystem to its maximum ecological effect.