秸秆颗粒改良剂对川西北高寒沙地土壤氮素和黑麦草生长的影响

为探明秸秆颗粒改良剂对川西北高寒沙地土壤氮素和黑麦草生长的影响,以农业废弃物(秸秆)为主要原料,复合聚丙烯酰胺、微生物菌剂和氮磷钾肥,加工成秸秆颗粒改良剂,设4个施用量水平(6,12,18,24t/hm2),以空白对照(CK0)和当地常规牦牛粪处理(CK1)为对照。结果表明:与CK0相比,秸秆颗粒改良剂和CK1均能显著增加土壤全氮、全氮密度、全氮储量和硝态氮含量,增加黑麦草株高、总根长、总根表面积、总根体积、平均根系直径和单株干重(p<0.05),达到增加土壤氮素含量和促进黑麦草生长的效果。与CK1相比,秸秆颗粒改良剂处理的平均全氮含量、全氮密度、全氮储量和硝态氮含量分别增加了12.50%,22.73%,20.90%和344.56%,黑麦草地上和地下部平均单株干重分别增加了57.50%和66.86%。增施秸秆颗粒改良剂可有效增加土壤氮素含量,黑麦草各生长指标也随改良剂施用量增加呈逐渐增加的趋势。施用量超过18t/hm2时,0—10cm土层的全氮、全氮密度、全氮储量和黑麦草各生长指标差异不显著。土壤氮素指标与黑麦草单株干重存在正相关关系,其中土壤全氮、全氮储量与黑麦草单株干重的相关性最高(r≥0.90**)。随改良剂施用量增加,外源养分淋溶率呈先降低后升高的趋势,在18t/hm2处有最小值。综合考虑土壤氮素含量、外源养分淋溶率和黑麦草生长的变化,秸秆颗粒改良剂以18t/hm2为川西北沙地土壤改良的最佳施用量。

Soil Nematode Response to Biochar Addition in a Chinese Wheat Field

While studies have focused on the use of biochar as soil amendment, little attention has been paid to its effect on soil fauna. The biochar was produced from slow pyrolysis of wheat straw in the present study. Four treatments, no addition (CK) and three rates of biochar addition at 2 400 (B1), 12 000 (B5) and 48 000 kg ha-1 (B20), were investigated to assess the effect of biochar addition to soil on nematode abundance and diversity in a microcosm trial in China. The B5 and B20 application significantly increased the total organic carbon and the C/N ratio. No significant difference in total nematode abundance was found among the treatments. The biochar addition to the soil significantly increased the abundance of fungivores, and decreased that of plant parasites. The diversity of soil nematodes was significantly increased by B1 compared to CK. Nematode trophic groups were more effectively indicative to biochar addition than total abundance.