【作者】 朱青；

【导师】 王兆骞；

【作者基本信息】 浙江大学 ， 生态学， 2008， 博士

【摘要】 针对我国西南中心地带的贵州山区红黄壤坡耕地退化的主要驱动因子和研究中存在的问题与不足,选择有代表性的贵州省南部罗甸县、边阳镇红黄壤坡耕地为研究对象,采用侵蚀小区径流泥沙观测法;中子活化Eu土芯定位示踪法;地面定位插钎法;土壤养分系统研究法以及坡耕地侵蚀退化防治的耕作措施（等高种植）、生物措施（林草覆盖）、工程措施（坡改梯）及综合措施,展开坡耕地退化机理和侵蚀退化防治措施研究。主要结论如下:红黄壤坡耕地退化主要表现为土壤的侵蚀退化、土壤养分退化和土壤酸化。1.红黄壤坡耕地侵蚀退化的关键因子是:1)土壤的可蚀性K值过高。裸露的红黄壤坡耕地,可蚀性K值的平均值达到0.376。不同种植制度和利用方式下的红黄壤坡耕地,可蚀性K值的平均值达到0.367。2)土壤的抗蚀性差,且变化不大。裸露的红黄壤坡耕地抗蚀性的平均值为69.49mm。而不同种植制度和利用方式下的红黄壤坡耕地,其抗蚀性变化甚微。3)降雨年内分配不均匀,而且降雨的侵蚀性极强。红黄壤坡耕地区雨量充沛,年平均降雨量达978.51mm。降雨的年内分配极不均匀,降雨一般集中在4-8月,合计降雨量占全年降雨量的80.55%。该区降雨转换成侵蚀性降雨的比例极高,达到75.96%,地表径流率高达80.37%。4)降雨的侵蚀力R值过高,危险性极大。红黄壤坡耕地区年R₁₀和R₃₀平均值分别为474.57和351.94。并在4-6月表现出提前于降雨的趋势,而此时正是田间换茬,地表裸露或作物生长幼苗期,地表覆盖低,由它引起水土流失发生的危险性极大。5)地表覆盖度不高。红黄壤坡耕地区年内月平均覆盖度达到28.26%,年内最高月平均覆盖度也才为48.72%。6)生物多样性低。红黄壤坡耕地区传统的耕作制度下,植物的物种数只达到2种,而分带轮作、粮草间作、植物篱种植和工程梯化方式下,这种以粮食生产为主的土壤,植物物种数也才达到3-6种。7)土壤的水分含量不高。裸露的红黄壤坡耕地土壤的水分含量平均值只为16.61%,而传统的种植制度下土壤的平均含水量只为18.90%。其它土地种植制度和利用方式下红黄壤坡耕地的水分含量平均值也才达到19.56%。8)坡度大。贵州省平均地表坡度为21.5°,红黄壤坡耕地研究区的地表坡度在11.3-34.7°之间。研究中发现在坡度为20°以下,传统耕作制度下的坡耕地都随坡度的增加,水土流失加大。9)人为因子加速坡耕地侵蚀退化。农事活动加速土壤的侵蚀不可忽视。传统的种植方式引发较严重的坡耕地水土流失。2.红黄壤坡耕地养分退化的途径为:土壤侵蚀引起的坡耕地养分的数量性退化、土壤吸附固定造成的坡耕地养分的有效性退化和作物收获造成的坡耕地生物消耗性退化。红黄壤坡耕地养分退化的机理主要表现在:1)水土流失造成的土壤养分损失量大。红黄壤坡耕地水土流失可造成的土壤养分损失在198.312-1536.121kg/ha.a。2)因土壤侵失而造成的土壤有机质和全钾损失大。红黄壤坡耕地土壤侵蚀造成的有机质损失达到90.964-708.937kg/ha.a,造成的全钾损失达到91.690-750.688kg/ha.a。3)径流造成土壤有效养分流失严重。红黄壤坡耕地水蚀引发的地表径流造成的土壤有效养分损失达到6.245-21.467kg/ha.a。4)径流造成土壤有效钾和硝态氮损失严重。红黄壤坡耕地水蚀引发的地表径流造成的土壤有效钾损失达到3.642-14.842kg/ha.a,硝态氮1.772-7.108kg/ha.a。5)侵蚀泥沙的养分富集率高,径流的养分浓度大。侵蚀泥沙的养分平均富集率都在1倍以上,对有效磷的富集能力最强,平均富集率达到8倍。径流带走的有效氮是泥沙的1.639-7.201倍,速效钾2.079-17.577倍。6)土壤对P、K、B的吸附固定率高,铵态氮与硝态氮转化快,土壤养分的有效性低。红黄壤坡耕地土壤对P,K,B有固定作用,平均固定率分别达到38.436%,26.915%和30.236%。铵态氮在土壤中15天内迅速下降,硝态氮在25天内迅速上升,之后10天内迅速下降达较低水平。7)作物收获是土壤养分输出的重要原因。不同种植制度和土地利用方式下因作物收获而带离土壤的养分总量达到127.296-1250.826kg/ha.a,占总的土壤养分输出量（即水土流失+作物收获而输出的土壤养分量之和）的15.23-86.57%,作物产量越高,生物量越高,土壤养分的输出量越大。8)作物的种类配置影响土壤养分输出。生产1kg黄豆、黄花菜、菊苣、油菜、紫苜蓿、红薯藤、玉米秸秆、玉米籽粒和红薯平均需要氮磷钾总养分分别为91.490g、78.567g、58.319g、54.077g、34.088g、29.120g、27.310g、22.009g和14.953g。对氮磷需求相当高的作物是黄豆、油菜和黄花菜;对钾需求较高的是菊苣、黄花菜和黄豆。因此不同的作物种类是生物消耗造成养分退化的关键因素。3.坡耕地土壤酸化的机理是:1)红黄壤坡耕地土壤的CEC和盐基饱和度都比较低,大部分土壤的CEC在11 Cmol（+）/kg左右,大部分土壤盐基饱和度在30%以下,而且变化不大。2)土壤中交换性铝离子浓度明显高于交换性氢离子。土壤中交换性铝离子浓度较高,总体平均值达7.188Cmol（+）/kg,土壤中氢离子浓度较低,总体平均值达0.688Cmol（+）/kg,铝离子浓度平均是氢离子的10倍。3)红黄壤坡耕地的土壤缓冲性能不高,土壤的平均酸缓冲性能高于碱缓冲性能。图解法求得的土壤酸缓冲容量在4-16Cmol/kg范围内,碱缓冲容量在2.5-14.0Cmol/kg之间。酸碱缓冲曲线拟合参数的方法中回归系数b的范围在-1.4981～-2.1297。铁、阳离子代换量、硝态氮和粘粒含量是土壤酸缓冲性能的主要影响因素,而锰、活性酸、有机质、硝态氮、pH、镁是土壤碱缓冲性能的主要影响因素。4.侵蚀针法操作简单,测定容易,省工省时,它能粗略测定土壤侵蚀量,可反映出侵蚀针点位上土壤的侵蚀或沉积动态变化。但周边的异常物和异常现象、侵蚀针细小的刻度、坡度等环境因素影响侵蚀针地上部分长度判读的精确性,从而极大影响侵蚀针的土壤侵蚀量计算结果,同时存在点面转换问题。中子活化Eu定位土芯示踪法可反映出土芯小面积上土壤的侵蚀或沉积动态变化,但不能测定地表径流。该方法毕竟是个新方法,操作规程有待于进一步完善。同样中子活化Eu定位土芯周边的异常物和异常现象影响其测量的准确性。中子活化Eu定位土芯示踪法测定的土壤侵蚀量也存在点面转换问题,且测定需精密仪器,成本较高。径流小区法实用性、灵活性都比较强,准确性高。可同时监测土壤流失量和地表径流量。可根据研究的目的展开多方面的研究。然而,径流小区法不能很好地反映坡面土壤侵蚀空间变异。另外,径流小区法需要修建径流场,需野外观察测定,工作量较大,成本较高。5.坡耕地侵蚀退化防治的关键技术有耕作措施、工程措施、林草措施和综合措施。它们都具有保持水、土、肥的作用,具有增加地表覆盖度、土壤根系含量和生物多样性的作用,具有提高土壤有机质、全氮、全钾、全磷、碱解氮、速效钾和缓效钾的作用。而不同措施的增产增收、土壤改良和土壤有效磷提升作用各有差异。植物篱措施具有很好的增产增收作用,并在实践中得到了较好的推广应用,产生了很好的效益。分带能作措施具有很好的提高土壤pH、全磷、全钾、有效磷和缓效钾的作用。粮草间作措施具有很好的提高土壤的抗蚀性、土壤水分和提高地表糙度的作用。工程措施具有很好的保持水、土、肥和降低坡度缩短坡长的作用。林地措施具有很好的改良土壤可蚀性、提高地表覆盖度、提高生物多样性、提高土壤有机质和全氮的作用。草地措施具有很好的提高土壤根系含量、提高土壤水分稳渗速率和土壤碱解氮的作用。综合措施具有很好的缩短坡长坡度的作用。不同措施的防治红黄壤坡耕地侵蚀退化综合效益,与农民习惯种植为对照,综合措施的效果最好,工程措施的效果次之,再其次是林草措施,最后是耕作措施。然而不同耕作措施其防治红黄壤坡耕地侵蚀退化效果也有不同。相比之下,植物篱耕作措施最好,其次是粮草间作,最后是分带轮作。6.研究中初步肯定红黄壤坡耕地研究区侵蚀性降雨临界值为9.1mm。初步明确红黄壤坡耕地研究区引起水土流失发生最关键的气候因子是降雨侵蚀力因子R₁₀。初步肯定红黄壤坡耕地研究区传统种植制度下耕地的土壤侵蚀临界坡度在20.00-24°之间,而植物篱种植下土壤侵蚀临界坡度在17.10-20.00°之间。初步对美国通用土壤流失方程的参数进行修正,得出红黄壤坡耕地研究区概念土壤流失方程表达式为:A=b·R·K·C·Pb值分别为混交林179,农民习惯668,分带轮作375,经果林195,工程梯化165,粮草间作219,植物条带214,草地202和裸坡耕地147。K值为0.379。C值分别为混交林0.851,农民习惯0.219,分带轮作0.385,经果林0.724,工程梯化0.853,粮草间作0.681,植物条带0.697和草地0.728P值分别为混交林0.191,分带轮作0.788,经果林0.353,工程梯化0.189,粮草间作0.409,植物条带0.388和草地0.348。初步得出裸露红黄壤坡耕地侵蚀模数达到25.8-631.2t/ha.a。达到中华人民共和国水利部采用土壤侵蚀模数拟定水蚀强度分级标准的Ⅲ-Ⅳ级范围,即中度侵蚀和强度侵蚀的范围。虽然各种种植制度和土地利用方式可减少土壤流失（侵蚀模数达到5.02-26.29t/ha.a）,但耕作制度下（农民习惯、分带轮作、粮草间作和植物篱）的坡耕地仍然具有较大的土壤侵蚀危险,经果林和草地的坡耕地在短期内也具有土壤侵蚀危险。初步明确红黄壤坡耕地研究区土壤酸化明显,pH值在4.420-5.790之间。初步肯定用公式Ⅱ计算土壤侵蚀性K值,其变异程度小;用诺谟图查值,变异程度也较小,且方法简便。它们是红黄壤坡耕地研究区土壤侵蚀性K值计算的较好方法。团聚状况、团聚度和机配比的变异程度相对较低,评价红黄壤坡耕地抗蚀性的规律性强,结果相似,因此它们是评价红黄壤坡耕地抗蚀性对相对较好的指标。初步肯定酸碱缓冲曲线拟合参数方法可较好定量求取这一特定区域土壤的酸碱缓冲容量。初步肯定采用模糊数学用于评价坡耕地不同措施防治土壤退化综合效益是可行的。更多还原

【Abstract】 A study with the runoff plot method,trace method of neutron activation of Eu fixed soil core,erosion stick method,system study method for soil nutrients and the protecting measures of tillage measures（contour planting）,bio-measures（forest and grass covering）,engineering measures（land terracing）,integrated measures on the sloping farming land degradation mechanism and the protecting measures against soil erosion degradation was conducted on the typical sloping farming land of yellowish red soil in Bian Yang township,Luo Dian county of southern Guizhou province,aimed at the main factors for sloping farming land degradation,the existed problems in the research and lack of such studies.The key results in the dissertation were as follows:The sloping farming land degradation mainly resulted from soil erosion degradation,soil nutrient degradation and soil acidification.1.The key factors responded for soil erosion degradation was:1)High soil erodibility K value.Such as the K value of bare sloping farming land of yellowish red soil was 0.376 and the average K value of sloping farming land of yellowish red soil under different cropping systems and land utilizations reached 0.367.2)Poor soil anticrodibility with slightly change with the times.The average anticrodibility of sloping farming land of bare yellowish red soil was 69.49mm.3)Rainfall distribution asymmetry in a year and its strong erosivity.Rainfall in the sloping farming land area of yellowish red soil was rich.The average annual rainfall was 978.51mm.Most events of rainfall happened during April to August.The precipitation during this times accounted for 80.55%of total precipitation.The transformation ratio of rain to aggressive rain reached 75.96%,runoff ratio was higher to 80.37%.4)High rainfall erosivity R and its strong fatalness.The average rainfall erosivity R₁₀and R₃₀in the sloping farming land area of yellowish red soil were 474.57 and 351.94 respectively. It occurred a bit before rainfall when there was few plants growth on the land and the vegetation coverage was low so that it had much possibility to bring a danger of water loss and soil erosion.5)Lower vegetation coverage.The average monthly vegetation coverage in sloping farming land area of yellowish red soil was only 28.26%. The highest monthly vegetation coverage in a year was only 48.72%.6)Low biodiversity. There were only two kinds of plants on farmer’s practice land in the sloping farming land area of yellowish red soil.There were only three to six kinds of plants on the land which under alley cropping systems,intercropping and contour cropping systems and terrace cropping systems,such kind of food production system.7)Low soil water storage.The average water contents of bare sloping farming land,farmer’s practice land and the land under different cropping systems and land utilizations of yellowish red soil were only 16.61%,18.90%and 19.56%respectively.8)Deep slope.The land slope in testing area was 11.3-34.7°.The average degree of ground slope in Guizhou was 21.5°.The water loss and soil erosion increased with the increase of slope which was under 20°.9)Farming activities.Farming activities accelerated soil erosion obviously.The traditional farming caused serious soil erosion.2.Soil nutrient degradation caused by soil erosion which conduced to soil nutrient loss by quantity,by soil absorption which resulted in low efficiency of soil nutrient, by crop harvest which caused soil nutrient consumption.The nutrient degradation on sloping farming land of yellowish red soil was mainly because 1)Lots of soil nutrient was loss by water loss and soil erosion.The more serious water loss and soil erosion was the more soil nutrient loss.The soil nutrient loss reached 198.312-1536.121kg/ha.a cased by water loss and soil erosion on sloping farming land of yellowish red soil.2)Soil organic matter and total K loss were serious,reached 90.964-708.937kg/ha.a and 91.690-750.688kg/ha.a respectively through soil erosion.3)Soil available nutrient loss was serious, reached 6.245-21.467kg/ha.a caused by runoff.4)Available K and NO₃-N loss were serious,reached 3.642-14.842kg/ha.a and 1.772-7.108kg/ha.a respectively.5) Nutrient enrichment rate of sediment was high and nutrient concentration of runoff was high.The nutrient content in sediment was one time more than that in soil.There was a high P nutrient enrichment rate in sediment.Phosphorus content in sediment was 8 times higher than that in soil.The amount of available N and K washed away by runoff were 1.639-7.201 times and 2.079-17.577 times higher than that of sediment respectively.6)Soil absorption rates of P,K and B were high.The transformation rate of NH₄-N to NO₃-N was high and soil available nutrient concentration was low. The average soil absorption rates of P,K and B were 38.436%,26.915%and 30.236% respectively.The content of NH₄-N decreased sharply within 15d,the content of NO₃-N increased fast within 25d and then decreased from the 25d to the 35d after fertilization.7)Crop harvest was the main factor for soil nutrient loss.There was 127.296-1250.826kg/ha.a total soil nutrient loss by crop harvest on sloping farming land of yellowish red soil under different cropping systems and land utilizations, it accounted for 15.23-86.57%of total soil nutrient loss which was the sum of nutrient loss caused by water loss and soil erosion and crop harvest.The higher crop yield and biomass were the more soil nutrient loss.8)Plant species and their combination effected soil nutrient loss.To producing 1kg of soybean,daylily flower,chicory, rapeseed,purple medic,sweet potato vine,corn straw,corn and sweet potato needed 91.490g、78.567g、58.319g、54.077g、34.088g、29.120g、27.310g、22.009g and 14.953g of NPK respectively.Soybean,rapeseed and day lily needed more NP,and chicory,day lily and soybean required more K for their growth.Therefore,difference of plant kinds was the key factor for soil nutrient loss by bio-consumption.3.The mechanism of soil acidification on sloping farming land of yellowish red soil was:1)Low CEC and base-saturation percentage.Soil CEC was about 11 Cmol（+）/kg and base-saturation percentage was less than 30%in general speaking.They changed slowly in sloping farming land of yellowish red soil.2)Concentration of exchangeable Al⁺³was much higher than concentration of exchangeable H⁺.Concentration of exchangeable Al⁺³was high to 7.188 Cmol（+）/kg and concentration of exchangeable H⁺ was low to 0.688Cmoal（+）/kg in average.Exchangeable Al⁺³concentration was 10 times higher than exchangeable H⁺ concentration in general.3)Base-acid buffering ability of sloping farming land of yellowish red soil was low.Acid buffering ability was better than base buffering ability.Soil acid buffering capacity was arranged from 4 to 16 Cmol/kg and base buffering capacity was from 2.5 to 14.0 Cmol/kg calculated through the diagram.The regression coefficient b form parameters-of-fit of acid-base buffering ability curve was ranged -1.4981～-2.1297.Iron,CEC,NO₃-N and clay impacted on acid buffering ability and Mn,AA,OM,NO₃-N,pH,Mg impacted on base buffering ability.4.Erosion stick method was simple,easy to operate,saving time and labour.It could measure soil erosion roughly.The changes of soil erosion and aggradations could show up with erosion stick method.However,Accuracy of reading the erosion stick length above the land was affected by abnormal objects and phenomenon surrounding the erosion stick,fine scale of erosion stick and land slope etc.so that the result of soil erosion was affected.There was a problem for erosion stick method that how to change the soil erosion on a point to soil erosion on a slope land.Trace method of neutron activation of Eu fixed soil core could show up the soil erosion and aggradations on the small area of Eu fixed soil core.But this method could not measure runoff.It was a new method;the operating process needed to further regulate.Also,abnormal objects and phenomenon surrounding the core could affect the accuracy of soil erosion calculation.How to change the soil erosion on a point to soil erosion on a slope land was not easy to be solved by this method.Additionally,it needed precision tool and cost was high.Runoff plot method was more practical,flexible and accurate.It could determine soil erosion as well as runoff.It could be used for many fields of studies according to the purposes.Nevertheless,it was not good to be used for study on the spatial variances of soil erosion and aggradations.In addition,runoff plot was set up on the field;determination and observation were on the field,it consumed lots man power.5.Key technologies of sloping land degradation control were tillage measures, engineering measures,forest-grass measures and integrated measures.All had the function of soil,water and nutrient conservation,could increase vegetation coverage, soil root content and enhance biodiversity,and could raise the concentrations of OM,total N,total K,total P,available N,available K and slowly available K.But their effects on increasing crop yields and incomes,soil improvement and raising soil available P were various.Alley cropping measures had very good effect on crop yield and income increase.Zone-rotation cropping measures could raise soil pH,total P,total K,available P and slowly available K well.Intercropping measures could enhance soil anticrodibility,increase soil moisture and land surface coarseness well. Engineering measures had very good effects on soil,water and nutrient conservation, and reduced land slope;shortened slope length rapidly.Forest measures could enhance soil anticrodibility and biodiversity,increase vegetable coverage,OM and total N. Grass measures could increase soil root content,water stable infiltration rate and available N.Integrated measures had good effects on shortening slope length and reducing land slope.Compared the integrated effects of different measures on erosion degradation control of sloping farming land of yellowish red soil with that of farmer’s practice,the best measures was integrated measures,the next was engineering measures,the next was forest-grass measures,and then the tillage measures.However,different tillage measures had different effects on erosion degradation control.Compared with them,alley cropping measures was the best measures for erosion degradation control.Intercropping measures was better for erosion degradation control than the zone-rotation cropping measures.6.Basically,the critical value of aggressive rainfall in sloping farming land area of yellowish red soil was 9.1mm.the most key climate factor of causing water loss and soil erosion was basically discovered that was rainfall erosivity R₁₀.The critical slope of soil erosion was basically found that were 20.00-24°and 17.10-20.00°for the sloping land under the traditional farming system and under the alley cropping system respectively.The concept soil erosion equation was basically worked out.It could be expressed as: A=b·R·K·C·P whereb of forest land,farmer’s practice land,zone-rotation cropping land,terraced cropping with fruit trees land,engineering cropping land,intercropping land,alley cropping land,grass land and bare sloping land were 179,668,375,195,165,219, 214,202 and 147 respectively.K was 0.379。C of forest land,farmer’s practice land,zone-rotation cropping land,terraced cropping with fruit trees land,engineering cropping land,intercropping land,alley cropping land and grass and were 0.851,0.219,0.385,0.724,0.853,0.681,0.697 and 0.728 respectively。P of forest land,zone-rotation cropping land,terraced cropping with fruit trees land,engineering cropping land,intercropping land,alley cropping land and grass and were 0.191,0.788,0.353,0.189,0.409,0.388 and 0.348 respectively。The erosion modulus of bare sloping farming land of yellowish red soil was 25.8-631.2t/ha.a which belonged to erosion intensityⅢ-Ⅳgraded by Water Conservation Ministry of People’s Republic of China.That was serious and very serious soil erosion.Although different cropping systems and land utilizations could reduce soil erosion the lands under tillage cropping system which included farmer’s practice,zone-rotation cropping,intercropping and alley cropping systems were still in danger of very serious erosion and the lands under terraced cropping with fruit and grass land were still in danger of erosion in recent years.Soil acidification was visible in sloping farming land area of yellowish red soil.The pH value was between 4.420-5.790.The variance of soil erodibility K calculated with formulaⅡwas small. The variance of soil erodibility K came from nomograph was small too and it was easy to get from nomograph.So they are good methods for K value calculation in sloping farming land area of yellowish red soil.The better indexes for evaluating soil anticrodibility of sloping farming land of yellowish red soil were soil aggregation state,degree of soil aggregation and ratio of sand and sum of clay and fine sand because their results of soil anticrodibility evaluation were similar and the variances of their value were small.The method of parameters-of-fit of acid-base buffering ability curve was good to get soil acid-base buffering capacity.It is feasible that fuzzy mathematics was used for integrated effects evaluation of sloping farming land erosion degradation control under different measures.更多还原