黄土高原半干旱区马铃薯连作对农田土壤生化性质及产量的影响

Effects of Potato Continuous Cropping on Biochemical Properties and Yield of Farmland Soil in Semi-arid Region of Loess Plateau

为探究黄土高原半干旱区马铃薯连作对农田土壤化学、生物学及产量的影响,以‘陇薯7号’马铃薯品种作为试验材料,共设5个处理(撂荒,CK1;小麦/豌豆/马铃薯轮作,CK2;连作2年马铃薯;连作4年马铃薯;连作6年马铃薯),分析不同处理对农田土壤化学、生物学及产量的影响。结果表明,轮作较连作处理显著增加了土壤有效磷和全氮的含量,且与连作2年、连作4年处理差异显著。各处理土壤总有机碳积累量为5.38~9.97 g/kg;0~20 cm(撂荒除外)土层土壤总有机碳积累量显著高于其他层次。随着连作年限的增加土壤蔗糖酶活性显著降低;土壤蔗糖酶、脲酶、过氧化氢酶3种土壤酶活性与土壤养分因子均呈极显著正相关。土壤微生物的数量大致由大到小排序依次为细菌>放线菌>真菌,细菌是土壤中的优势菌,数量占95%以上。有机质、碱解氮与马铃薯产量呈极显著负相关(P <0.01),而全氮则与马铃薯产量呈显著正相关(P <0.05)。土壤化学、生物学因子的综合变化可能是导致甘肃中部干旱半干旱地区马铃薯连作障碍形成的重要原因。

Five treatments(abandonment, CK1;wheat/pea/potato rotation, CK2;potato continuous cropping for two years;potato continuous cropping for four years;and potato continuous cropping for six years) were set up with potato variety ’Longshu 7’ as experimental material in order to explore the effects of potato continuous cropping on soil chemistry, biology and yield in semi-arid region of Loess Plateau. The effects of different treatments on soil chemistry,biology and yield were analyzed. Rotation significantly increased the contents of available phosphorus and the total nitrogen in soil compared with continuous cropping, and there were significant differences between rotation and continuous cropping for two years and four years. The total organic carbon accumulation in each treatment was 5.38-9.97 g/kg, and the total organic carbon accumulation in 0-20 cm soil layer(except the treatment abandonment) was significantly higher than that in other layers. With the increase of continuous cropping years, soil sucrase activity decreased significantly, and soil sucrase, urease and catalase activities were high significantly positively correlated with soil nutrient factors. The number of soil microorganisms ranked from large to small in order of bacteria >actinomycetes > fungi. Bacteria were the dominant microorganisms in soil, accounting for more than 95%. Organic matter and alkali-hydrolyzed nitrogen contents were negatively correlated with potato yield(P < 0.01), however, total nitrogen content was positively correlated with potato yield(P < 0.05). The comprehensive change in soil chemical and biological factors might be an important reason for the formation of potato continuous cropping obstacles in arid and semi-arid areas of central Gansu Province.