一稻两鸭共作对稻田土壤养分动态的影响

Dynamics of soil nutrients under rice-duck farming system with two-batch-duck raising

鸭稻共作是有效减少化肥和农药施用的重要技术,对稻田土壤养分消耗具有一定的缓冲和调控作用。但在鸭稻共作有机生产模式中,外源性化肥投入的缺乏常常成为水稻高产的限制因素。为更好地解决有机种植中土壤养分供应的问题,对常规鸭稻共作进行了调整,建立了2种"一稻两鸭"共作生态农业模式。通过田间试验对常规稻作、常规鸭稻共作、一稻两鸭轮养及一稻两鸭套养4种种植模式下的土壤养分进行定位监测。结果表明:相对于常规稻作,3种鸭稻共作模式均能在一定程度上提高土壤全钾、全氮的含量,同时减小碱解氮的消耗。与比生产前期相比,生产结束后常规水稻种植模式下土壤有机质含量有所下降,而3种鸭稻共作模式下土壤有机质含量比生产前期均有不同程度的增加。4种种植模式下土壤全磷含量在生产结束后均有不同程度的下降,然而一稻两鸭套养和一稻两鸭轮养模式下土壤全磷含量的降低程度低于常规稻作。早稻生产结束后,一稻两鸭套养和一稻两鸭轮养模式下的土壤全磷含量比常规稻作分别高出13.53%和11.01%。与常规鸭稻共作模式相比,一稻两鸭轮养和套养模式增加了全氮以及全钾有机物的积累,同时减缓了碱解氮、速效磷、速效钾含量的下降。晚稻生产结束后,一稻两鸭套养模式下土壤碱解氮、速效磷和速效钾的含量分别比常规鸭稻共作模式高出3.7%,10.39%和7.59%。产量测定结果表明,早稻时期一稻两鸭套养模式下的水稻产量比常规鸭稻共作模式高12.90%,晚稻时期则比常规鸭稻共作高12.19%。一稻两鸭共作模式中,由于两批鸭子的存在,其排便和中耕作用几乎贯穿于水稻的整个生长发育过程,因此培肥效果与常规鸭稻共作相比有了进一步的提高,对系统内的养分循环利用起到了更好的促进作用。

Rice-duck farming is an organic farming system for the maintenance of soil fertility with duck manure. Such system helps reduce the pollutants induced by chemical fertilizers and pesticides. Nevertheless, the productivity of such organic farming system is frequently limited due to the lack of sufficient chemical fertilizers. In order to supply sufficient soil nutrients, this paper proposes two-batch-duck raising with rice farming, including the rotational pasturing with two-batch-duck raising （RP） and the mixedpasturing with two-batch-duck raising （MP）. The soil nutrients in these two proposed systems were monitored and compared with the ones in conventional rice monocropping （CR） and conventional rice-duck farming system （CD） through filed experiments. Compared with the CR treatment, the results showed that CD, RP and MP treatments led to the increase in the total N and total K contents. In addition, treatments including CD, RP and MP all resulted in less consumption of alkali-hydrolysis N. The soil organic matter （SOM） in these three treatments had different levels of increases after harvesting whereas it decreased in the CR treatment. All four treatments experienced significant reductions in the total P in soil after harvest, of which less reductions were observed in the RP and MP treatments as compared to the CR treatment. Specifically, the total P in the RP and MP treatments post early rice harvest was 13.53% and 11.01% higher than that of CR treatment, respectively. Compared with the CD treatment, both two-batch-duck raising systems led to the increased accumulation of SOM, total nitrogen and total potassium contents, and delayed the reductions in alkali-hydrolysis N, available P, available K, and total P in soil. Compared with the CD treatment, the contents of alkali-hydrolysis N, available P and available K in the MP treatment post harvest were increased by 3.7%, 10.39% and 7.59%, respectively. Besides, the rice yield in MP treatment was increased by 12.90% in the early rice season and 12.19% in the late rice season compared to that of CD treatment. These findings indicate that both the RP treatment and MP treatment outperform the CD treatment on improving soil fertility and nutrient utilization in paddy fields. This should be attributed to the increase in the pasture time in the two proposed systems with more duck feces and the effect of intertillage and muddying during all the growth stages of rice.