长期定位条件下不同轮作系统的土壤肥力数值化综合评价

Soil Fertility Numerical Value Comprehensive Evaluation of Different Rotation System under the Long-term Positioning Conditions

在长期轮作与施肥定位试验基础上,对黄土高原沟壑区不同轮作系统土壤肥力进行数值化综合评价。以休闲地为对照,分析比较长期定位条件下苜蓿连作、玉米连作、小麦连作、玉米小麦轮作及粮豆3年轮作的土壤容重、养分含量及酶活性,应用相关性分析及模糊数学原理对长期定位施肥的土壤肥力进行数值化综合评价。结果表明:(1)除苜蓿连作土壤过松外,玉米连作、小麦连作、玉米小麦轮作及粮豆3年轮作土壤松紧度适宜,苜蓿连作土壤养分含量远高于玉米连作、小麦连作、玉米小麦轮作及粮豆3年轮作,苜蓿连作的土壤酶活性也较高。不论是连作还是轮作,长期定位施肥后的土壤松紧度、养分含量及土壤酶活性均明显高于休闲地。(2)苜蓿连作、玉米连作、小麦连作、玉米小麦轮作及粮豆3年轮作IFI分别为86.47、56.36、64.13、64.67、63.08,均显著高于休闲地(IFI 39.49)。苜蓿连作的土壤肥力水平显著高于玉米连作、小麦连作、玉米小麦轮作及粮豆3年轮作。(3)提出土壤肥力数值化综合评价时土壤容重的隶属度函数计算方法。因此,轮作能提高土壤养分含量,促进土壤有机质、氮、磷、钾含量的积累,是提高土壤肥力水平的主要途径;不同作物及轮作方式对土壤的培肥能力不尽相同,与作物种类及其生长习性有关,在黄土高原气候和土壤条件下,苜蓿连作对培肥土壤具有较好的作用;针对不同轮作系统采取适当措施,可提高不同轮作系统培肥土壤的能力;对土壤肥力进行数值化综合评价时,土壤酶活性转折点的取值及分级标准有待进一步研究和探索,以达到更科学、合理的评价土壤的肥力水平。

Based on long-term rotation and fertilizer test,a soil fertility numerical value comprehensive evaluation on different rotation system had been made in the gully region of the loess plateau.Contrasted with the bare land,the soil bulk density,nutrient content and enzymatic activity of alfalfa continuous,corn continuous,wheat continuous,corn wheat crop rotation and grain-bean 3-year rotation were analyzed and the correlation analysis and fuzzy mathematics theory were used to comprehensively evaluate the soil fertility under the long-term positioning conditions.The results showed that under corn continuous,wheat continuous,corn-wheat crop rotation and grain-bean 3-year rotation except for alfalfa continuous cropping,soil firmness were appropriate.The soil nutrient content under alfalfa continuous cropping was far higher than the corn continuous cropping,wheat continuous cropping,corn wheat crop rotation and grain bean 3 years＇ rotation.The soil enzyme activity of alfalfa continuous cropping was also higher.Under continuous cropping and/ or rotation,the soil firmness,nutrient content and soil enzyme activity were significantly higher than that of fallow land after long-term fertilization.The IFI of soil fertility levels of alfalfa continuous,corn continuous,wheat continuous,corn wheat crop rotation and grain bean 3 years＇ crop rotation respectively were 86.47,56.36,64.13,64.67 and 63.08,and were significantly higher than those of the fallow land（IFI 39.49）.The soil fertility levels of alfalfa was continuous significantly higher than corn continuous,wheat continuous,corn wheat crop rotation and grain bean 3 years＇ crop rotation.The calculation method of soil bulk density＇s membership function was put forward to carry through numerical value comprehensive evaluation soil fertility.In conclusion,crop rotation could improve the soil nutrient content,promote the accumulation of the soil organic matter,nitrogen,phosphorus,potassium content and had become a main route to improving soil fertility levels.The fertility buildup ability of different crop and rotation way was different which related to crop species and its growth habit.The appropriate measures could be taken according to different crop rotation systems to improve their soil fertility buildup ability.On soil fertility for numerical comprehensive evaluation,the soil enzyme activity turning point of value and grading standards need further study and exploration for a more scientific and reasonable evaluation to the soil fertility level.