通过保护性农业调节土壤养分和有机质提高土壤生产力.ppt

Improving Soil Productivity by Managing Nutrients and Organic Matter with Conservation Agriculture 通过保护性农业调节土壤养分和有机质提高土壤生产力,Xiying Hao, Yuxia Li, Ph.D. Agriculture & Agri-Food Canada 郝熙英,李玉霞 加拿大农业与农业食品部 Haoxyagr.gc.ca http:/res2.agr.ca/lethbridge/scitech/xiying_e.htm,Soil土壤,Medium for crops to anchor and grow是固定作物和作物生长的媒介 Holds water, air and nutrients储存水分、空气和养分 Essential to life on earth对地球生命十分重要 We need to take care of our soil so that it will help us produce the food we need for generations to come我们要珍惜土壤，是其能产出我们及后代所需的食品,Soil degradation is caused by土壤退化的原因 Erosion水土流失 Loss of organic matter有机质减少 Intensive tillage and soil compaction过度耕作及土壤压实 Salinization盐渍化 Contamination and污染和 Acidification酸化 Soil degradation is the major cause of decline in soil productivity土壤退化是土壤生产力降低的主要原因,What happens when soil is mismanaged 土壤管理不善时将会发生什么,Loss of most fertile top soil 表层土壤肥力丧失 Loss of organic matter有机质流失 Loss of nutrients养分流失 Loss of microbes微生物消失 Crop has to root into lower infertility soil underneath with poor soil structure作物只能在结构差、肥力差的底层土壤扎根 Lower infiltration and water holding capacity土壤渗透和持水力降低 More prone to runoff and water erosion更易导致径流和水蚀 The lost top soil with valuable nutrients and organic matter could end up in surface water, causing pollution流失的表土中的养分和有机质最终会流入水体，产生污染,What happens to soil when it is degraded 土壤退化的后果,Dr. Jeff Tullbrg 澳大利亚,土壤有机质与降雨入渗率的比较,注:小时降雨量总计80毫米,SOM level in some Alberta soil 部分阿尔伯特与五原土壤有机质水平,Requires higher fertilizer input 需要更高的肥料投入 Less available nutrients in soil土壤中有效养分低 Less released during the growing season as total amount of nutrients is low and fewer microbes exist to convert the nutrients to available form由于总养分低使得整个生长季养分释放少、土壤中促进养分转换的微生物少 Prone to drought or flooding problems as soil has a lower infiltration rate and smaller water holding capacity由于土壤渗透低、持水差，容易导致干旱和洪灾 Increased machinery power requirement and crop production cost增加能源消耗和生产成本 Risk of crop failure will be high农业生产风险增加,Crop production in degraded soil退化土壤上的作物生产,Retain crop residue on soil surface留秸秆、少耕与免耕 Keep a taller cereal stubble保留高的谷物残茬 Grow cover crops (green manure) , crop rotation with legume or forage种植覆盖作物（绿肥）,豆科与牧草 Improve soil structure (aggregation) through livestock manure application通过增施农家肥改良土壤结构（团粒性） Reduce sub-soil compaction减少土壤压实 The above measures may also lead to increases in soil organic matter (SOM) content, the heart of soil productivity通过采取以上措施，也可以使作为土壤生产力核心的有机质含量增加(需要3-5年的时间),Restoring soil productivity土壤生产力的恢复,SOM is one of the most important components of soil土壤有机质是土壤最重要的成分之一 Consists of a variety of components 由不同成分组成 raw plant residues and microorganisms (1 to 10 %) 作物残茬和微生物（1-10） “active” organic fraction (10 to 40 %) “活性“有机质（10-40%） resistant or stable organic matter (40 to 60 %) also referred to as humus长效或稳态有机质（40-60%），也叫胡敏酸,Soil Organic Matter (SOM)土壤有机质,The “active” and some of the resistant soil organic components, together with microorganisms, bind small soil particles into larger aggregates (important for good soil structure, aeration, water infiltration and resistance to erosion and crusting) ”活性“和一些稳定的有机质和微生物一起将土壤颗粒形成较大的团粒（这有利于形成好的土壤结构、增加透气性、水分的渗透和防止水土流失与土壤表面板结）,SOM and Soil Structure土壤有机质和土壤结构,The resistant or stable fraction contributes to nutrient holding capacity and soil color. This fraction of organic matter decomposes very slowly and therefore has less influence on soil fertility than the “active” organic fraction 稳定的土壤有利保持土壤养分和颜色，这些小的有机质分解缓慢，因此对土壤肥力的影响小于”活性”的。 SOM improve soil structure, maintain tilth, and minimize erosion 有机质能改善土壤结构、保持土壤的可耕性和降低流失。,SOM and Soil Structure土壤有机质和土壤结构,SOM does not add any “new plant nutrients but releases nutrients in a plant available form through the process of decomposition有机质并不是增加任何”新“养分，而是通过分解可以释放植物可利用的养分 To maintain this nutrient cycling system, the rate of addition from crop residues and manure must equal to the rate of decomposition保持系统养分循环，增施的作物残茬和农家肥必须与分解的速率相当 If the rate of addition rate of decomposition, soil organic matter will increase. 如果加入的量分解的量，土壤有机质增加 A steady state exists when the rate of addition is equal to the rate of decomposition.只有加入的量等于分解的才会达到稳定,Why SOM is important 为什么有机质很重要？,Managing SOM土壤有机质管理,SOM cannot be increased quickly even when management practices that conserve soil organic matter are adopted土壤有机质的增加不可能太快，即使采取的措施有利于土壤有机质的保持 Only a small fraction of crop residues added to soil remains as soil organic matter只有小部分的秸杆还田转换成有机质 After an extended period of time, the return of all crop residues and the use of forage in rotation with cereals and oilseeds/legume may significantly increase SOM, particularly, the “active” fraction.通过一段时间，秸杆还田和采用饲料作物与谷物和油料/豆类的轮作体系会显著增加土壤有机质，特别是”活性“部分,作物留高茬可挡住积雪,1960-1975 夏季休耕期间用除草剂替代耕作，除草剂有限 1975-1985 集中开发合适的免耕播种机械，除草剂昂贵 1985-1990 免耕机成功/除草剂价格下降 1990-1995 作物轮作及杂草综合治理 1995-现在 降低生产费用，降低除草剂，降低温室气体效应和提高抗自然灾害的能力,不同耕作体系与经济效益的比较,Fertilization and SOM肥料与土壤有机质,Applying fertilizers will generally increase soil organic matter because the increased crop growth returns larger amounts of residue to the soil一般而言，施肥可以增加产量，进而增加还田的秸杆量，增加有机质的含量 Applying extra fertilizer when adding straw residue will keep the C/N ratio close to microbe need, so less carbon is lost as CO2增加秸杆时，可以通过增施肥料以保持土壤C/N比在微生物需要的范围，因此减少土壤碳以CO2形式散失，增加有机质的含量 Applying fertilizer meets the nutrient needs of both crops and microbes which decompose crop residue施肥时应考虑即满足作物营养和微生物分解秸杆的需求,Crop Rotation and SOM轮作与土壤有机质,Perennial forage is effective as a binding agent in soil aggregation多年生饲草根系密植能有效地改变土壤结构 Nitrogen fertility is enhanced by the growth of legumes通过种植豆类作物增加土壤供氮能力 Increases permeability of dense subsoils because of the deep penetrating tap roots of perennial legumes especially alfalfa由于豆科牧草是深根作物（特别是苜蓿），可以起到自然深松土的作用 Reduces rate of organic matter decomposition in the absence of tillage少耕和免耕，可以降低土壤有机质的分解率，增加有机质在土壤中的含量,Summary 结论,To improve soil productivity, we will need to stop soil erosion and increase SOM 为了增加土壤生产能力，必需控制土壤流失并增加土壤有机质 Cultivation generally causes a decline in SOM