长期施肥对南方黄泥田冬春季杂草群落及其C、N、P 化学计量的影响

在福建黄泥田长期定位施肥试验的第27年,研究了不同施肥处理对冬春季稻田杂草群落及其C、N、P化学计量的影响。结果表明,与不施肥(CK)相比,化肥+牛粪(NPKM)、化肥+秸秆还田(NPKS)及单施化肥(NPK)处理的杂草Shannon均匀度指数(E)降低0.03~0.07个单位,NPKM与NPKS处理还同时降低了Margalef物种丰富度指数(DMG),而表征综合量度的Shannon多样性指数(H′)则降低0.02~0.16个单位。各施肥处理的杂草生物量较CK增加89.6%~214.7%。不同施肥处理还提高了杂草N、P、K养分含量,尤其是NPKM处理,各施肥处理养分积累顺序表现为:NPKM>NPKS>NPK。此外,各施肥处理降低了杂草C/N与C/P计量比值。植株C/N、C/P、N/P与土壤C/N、C/P、N/P及生物量间呈一定的显著相关。不同施肥处理影响杂草多样性及其养分吸收,施肥处理的杂草养分储量可观,培肥潜力大。杂草的C、N、P计量比一定程度上可反映土壤C、N、P计量特征。

Effects of long-term fertilization on weed community characteristics andcarbon, nitrogen and phosphorus stoichiometry during winter-springseason in yellow-clay paddy fields of South China

As an important agronomic measure,fertilization affects not only crop growth,but also field weeds and community composition.However,the effects of different fertilization on weed community characteristics are still not fully understood.To that end,a long-term experiment was set up in 1983 at Fujian Experimental Observatory Station,a station for the monitoring(via experi-mental plots) of long-term farmland conservation practices.The station belongs to the Ministry of Agriculture and is located at 119°04’10" E and 26°13’31" N.The soils at the station are the typical yellow-clay paddy soils originating from foot-slope deposited low-hilly red soils of mid-low-yield paddy fields.The influences of different long-term fertilization schemes on the characteristics of field weed communities and carbon(C),nitrogen(N) and phosphorus(P) stoichiometry during winter-spring seasons were investi-gated.The main aim was to lay the scientific basis for southern paddy soil fertility improvement and weed management and utiliza-tion.The results showed that compared with the control(no fertilization,CK),Shannon uniform index(E) was 0.03~0.07 lower in the treatments of chemical fertilizer plus cattle manure(NPKM),chemical fertilizer plus straw(NPKS) and chemical fertilizer(NPK).Margalef abundant index(DMG) also dropped in NPKM and NPKS treatments.Shannon diversity index(H′),a comprehensive indi-cator,was 0.02~0.16 lower in fertilization treatments.Compared with CK,weed biomass increased by 89.6%~214.7% in all fertiliza-tion treatments.Weed N,P and K contents increased as well,and was most significant for NPKM treatment.In terms of accumulated nutrients,the treatments rank of paddy soils was NPKM > NPKS > NPK.Furthermore,weed C/N and C/P ratios dropped in all fer-tilization treatments.Some significant correlations were noted among weed C/N,C/P and N/P ratios and C/N,C/P,N/P ratios of soil and biomass.Different fertilization schemes influenced weed diversity and nutrient uptake.Also weed nutrient accumulation was considerable in all fertilization treatments,with enormous fertility,C and N.To some extent,ratio among C,N,P of weeds reflected C,N and P stoichiometry of soils.