碳氮添加对雨养农田土壤物理性状的影响

为探明添加不同碳源及不同量氮肥4年后对土壤物理性质、产量的影响,依托布设于甘肃省定西市安定区李家堡镇的不同碳源田间定位试验,设置2种碳源(生物质炭15t/hm^2,秸秆4.5t/hm^2),3个氮肥施用量(0,50,100kg/hm^2),共计9个处理。研究了生物质炭、秸秆配施氮肥对试区土壤容重、总孔隙度、土壤饱和导水率、土壤团聚体稳定性、产量的影响。结果表明:较之无碳添加处理,添加生物质炭或秸秆均可改善土壤物理性质,但生物质炭效果最好。秸秆输入对0-5cm土层土壤容重的降低和总孔隙度、水稳性团聚体稳定性的提升具有显著效应,对土壤饱和导水率和0-30cm各土层机械稳定性团聚体稳定性的提升具有显著效应,而生物质炭对0-30cm各土层的土壤物理指标的改善均具有显著效应。氮素添加对土壤物理指标影响较小。生物质炭、秸秆、氮素均可促进作物增产,总体而言,生物质炭增产效果优于秸秆,尤其是生物质炭15t/hm^2+施纯氮100kg/hm^2处理。因此,添加生物质炭更有利于该区土壤物理性质的改善和产量的增加。

Effect of Carbon and Nitrogen Addition on Soil Physical Properties in Rainfed Farmland

A 4-year field trial was conducted at the Rained Agricultural Experimental Station of Gansu Agricultural University in the Loess Plateau of central Gansu Province. Experimental treatments of carbon (C) addition sources included straw, biochar and no C addition, and each C treatment was combined with three nitrogen (N) addition levels, 0, 50 and 100 kg/hm² respectively. The experimental set-up was a randomized complete block design with three replications. The aim of the study was to determine the effect of different C sources and different N levels on soil bulk density, total porosity, soil saturated hydraulic conductivity, soil aggregate stability and crop yield. The soils were sampled at three layers (0-5, 5-10 and 10-30 cm) per plot. The results showed that compared with no Caddition treatments, application of biochar or straw increased soil total porosity, reduce bulk density, especially biochar addition, it had significant effects on reducing bulk density and increasing soil total porosity at all three observed depths, the effects of straw addition, however, was observed at 0-5 cm layer. Both straw and biochar could significantly improve soil saturated hydraulic conductivity, but the effect of biochar addition was greater than that of straw addition plots. Among observed layers, in comparison with no C addition plots, both biochar addition and straw addition could enhance the amount of soil mechanical stable aggregates and MWD significantly, and the effect of biochar addition was greater than that of straw. The amount of soil water stable aggregates and MWD were increased more significantly in biochar addition soils than those in no C addition and straw addition treatments. Hence, both biochar and straw treated soils improved soil physical properties, and biochar showed the greatest effects. The effects of biochar, straw and nitrogen on crop yield were significant, but biochar was the best, especially biochar 15 t/hm² + nitrogen 100 kg/hm². As a whole, biochar addition was proposed for the sustainable agricultural development in the Loess Plateau of central Gansu Province.