稻草高茬-紫云英联合还田改善土壤肥力提高作物产量

研究旨在探讨稻草留高茬套种绿肥、稻草-绿肥联合还田下的生产及土壤肥力特征,为南方稻区综合利用稻草和绿肥提供理论及技术支撑。2012—2016年设置定位试验,研究高茬稻草-绿肥联合还田下的绿肥和水稻产量、土壤碳氮库活性及其他养分特征。试验包括5个处理:冬闲+稻草不还田(CK),冬闲+稻草全量还田(RS),冬种紫云英+稻草不还田(MV),冬种紫云英+稻草低茬全量还田(MV+LRS),冬种紫云英+稻草高茬全量还田(MV+HRS),各处理施用等量化肥。结果表明:稻草-绿肥联合还田提高绿肥产草量及其含氮量,与MV相比,分别增加了13.1%和6.8%(MV+LRS)、32.2%和5.2%(MV+HRS);增加水稻产量,以MV+HRS处理最高,4 a平均产量较RS、MV增加556.8和412.8 kg/hm2。2013和2015年,MV+HRS处理水稻产量高于MV+LRS。稻草-绿肥联合还田培肥地力效果明显,土壤有机质、全氮含量均比CK、RS和MV增加;且联合还田下有效养分提升更为全面。与稻草和绿肥单独应用相比,稻草-绿肥联合还田还能提升土壤微生物量氮及可溶性有机碳氮含量。可见,稻草-绿肥联合还田能够改善绿肥生长、提高水稻产量、提升土壤肥力;其中,高茬稻草与绿肥联合还田下的紫云英和水稻产量最高,土壤肥力也优于低茬处理,是综合利用稻草和绿肥资源的较好方式。

Co-incorporation of high rice stubble and Chinese milk vetch improving soil fertility and yield of rice

Abstract: Rice straw return and green manure cultivation in winter fallow season are 2 effective ways of improving soil fertility in south China. Due to the relatively stable carbon to nitrogen ratio, either the rice straw return or green manure cultivation alone has its own limits in practice. Recently, the combined application of green manure and rice straw has been developed, while little is known about the impacts on crop yield and soil fertility. A field trial was conducted at an experimental station managed by National Engineering and Technology Research Center for Red Soil Improvement in Fengcheng, Jiangxi Province, China to explore effects of remaining high rice stubble, inter-planting green manure (Chinese milk vetch, Astragalus sinicus L.) and co-incorporation of rice straw and green manure on double rice and green manure yield and soil fertility. Field experiments were conducted in a rice-rice-winter fallow or rice-rice-Chinese milk vetch (MV) rotation system. A total of 5 treatments with different cultivation practices were included, (i) CK, rice-rice-winter fallow without rice straw return; (ii) RS, rice-rice-winter fallow with rice straw return; (iii) MV, rice-rice-MV without rice straw; (iv) MV+LRS, rice-rice-MV with return of low stubble (0 cm) of rice straw; (v) MV+HRS rice-rice-MV with return of high stubble (30 cm) of rice straw. The results showed that co-incorporation of RS and MV significantly increased fresh yield and nitrogen content of MV plants by 13.1% and 6.8% in MV+LRS and 32.2% and 5.2% in MV+HRS than those in MV alone, respectively. The average yield of double rice yield over the 4 years was significantly increased by 556.8 and 412.8 kg/hm2 in MV+HRS than in RS and MV, respectively. Compared to CK, the soil organic matter (SOM) content was significantly increased by 6.8% to 8.0% in RS and MV, the total nitrogen (TN) was marginally affected by the 2 treatments. Compared to CK, the soil inorganic N content was significantly decreased in treatments with RS and MV alone, while the available K was increased in RS. Different from soil inorganic nitrogen, manure treatments greatly improve available P content and the treatment of MV with HRS increased the available P by 18.0%. However, the treatments with rice straw could greatly increased soil available K by 8.0% (RS), 9.2%(MV+LRS) and 22.8%(MV+HRS), respectively. The soil microbial nitrogen were also significantly enhanced in the combinations than in MV or RS alone (P<0.05). The dissolved organic carbon and nitrogen were greater in the manure-rice straw combination treatments than CK. The treatments with rice straw enhanced the proportion of microbial biomass C in SOC and that of microbial biomass N in TN. Compared with the rice straw and manure alone, the co-incorporation of rice straw and manure increased the proportion of dissolved organic N in TN and inorganic N in TN. Collectively, the co- incorporation of rice straw and green manure could improve the rice yield and soil fertility in present conditions. The practice of keeping high stubble of rice straw standing in the field and returned together withgreen manure had the great promise to maintain and improve soil fertility and rice yield in south China.