不同施肥量对绿肥产量和养分积累的影响

大田试验条件下研究不同氮、磷、钾肥用量对绿肥[豆科绿肥紫云英(Astragalus sinicus L.)和禾本科绿肥看麦娘(Alopecurus aequalis Sobol.)]产量及养分积累量的影响。试验结果表明,施肥能显著增加绿肥产量,绿肥鲜草产量较不施肥处理增加42.8%~311.1%,与缺素处理相比,氮、磷、钾肥的增产率分别为57.1%~177.5%、27.8%~178.7%、14.2%~32.4%。两种绿肥的鲜草产量均随氮、磷、钾肥施用量的增加而增加,中、高水平的氮、磷肥用量下看麦娘的产量均高于紫云英,所有钾肥处理的看麦娘产量均高于紫云英。绿肥的养分积累量均随施肥量的增加而增加,中高水平的氮、磷肥用量下看麦娘的氮、磷积累量高于紫云英,不同钾水平下的看麦娘钾积累量均高于紫云英。氮、磷、钾肥用量分别为112.5 kg(N).hm?2、19.7 kg(P).hm?2、37.5 kg(K).hm?2时,两种绿肥总产量及碳、氮、磷、钾积累量最高,分别为49 424 kg.hm?2和3 212 kg(C).hm?2、151 kg(N).hm?2、19.8 kg(P).hm?2、156 kg(K).hm?2。此时看麦娘产量、碳、氮、磷、钾积累量分别占总量的59.0%、65.7%、66.3%和64.4%。紫云英田间自然洒种的看麦娘无成本投入且养分积累量高,不失为一种优质绿肥。

Effect of fertilizer amount on yield and nutrient accumulation of green manures

The abundant winter fallow fields in southern China can be used to cultivate green manure crops. It has been demonstrated that returning green manure to farmlands supports sustainable agricultural development. Green manure yield has, however, decreased sharply in recent years, seriously limiting large-scale applications of green manure in agricultural production. A field experiment was conducted to study the effect of nitrogen (N), phosphorus (P) and potassium (K) fertilizers on yield and nutrient accumulation of green manure. The crops considered for use as green manure in this study included Astragalus sinicus L. and Alopecurus aequalis Sobol., which were studied in 11 treatments. A. aequalis was a natural reseeding gramineae grass grown in A. sinicus field. For more accurate analysis, 2 types of green manure were separately harvested and weighted. Results showed that fertilizer application significantly increased fresh yield of two plants. Compared with non-fertilizer treatments, yield under fertilizer treatments increased by 42.8%~311.1%. Compared with nutrient deficiency treatment, N, P and K treatments increased yield by 57.1%~177.5%, 27.8%~178.7% and 14.2%~32.4%, respectively. Fresh yields of the 2 green manures increased with increasing application rates of N, P, K. Fresh yield of A. aequalis was higher than that of A. sinicus under the medium and high application amounts of N and P fertilizers. For all K fertilizer treatments,A. aequalis produced higher fresh yield than A. sinicus. Green manure nutrient accumulation increased with increasing N, P, K application rate. Under medium and high N and P treatments, N and P accumulations in A. aequalis were higher than those in A. sinicus. However, K accumulation in A. aequalis was higher than that in A. sinicus for all K treatments. With 112.5 kg·hm^-2, 19.7 kg·hm^-2 and 37.5 kg·hm^-2 of N, P and K fertilizer application rates, total yield and C, N, P and K accumulations of two plants were maximum, reaching 49 424 kg·hm^-2, 3 212 kg·hm^-2, 151 kg·hm^-2, 19.8 kg·hm^-2 and 156 kg·hm^-2, respectively. Meanwhile, yield and C, N, P and K accumulations in A. aequalis accounted for 59.0%, 65.7%, 66.3% and 64.4% of the above total amounts. Those indicated that A. aequalis was a high quality green manure with a little input.