(1.4)--Multiple Cropping system耕作制度耕作学.PDF
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1、Chapter VMultiple Cropping Systems:A Basis for Developing anAlternative AgricultureDr.Stephen R.GliessmanEnvironmental StudiesUniversity of CaliforniaContentsPageAbstract.69Introduction.69Concepts and Definitions.70The Basis of Multiple Cropping.71Yield Advantages of Crop Mixtures.71General Resource
2、 Use.73Specific Resource Use,Conservation,and Management.75Agroforestry:A Multiple Cropping System.79Socioeconomic Implications of Multiple Cropping Systems:Perspectives for the Future.80References.82List of TablesTable No.Pagel.Definitions of the Principle Multiple Cropping Patterns.712.Related Ter
3、minology Used in Multiple Cropping Systems.713.Biological and Physical Factors:The Advantages and Disadvantages of MultipleCropping Systems Compared to Sole-Cropping or Monoculture Systems.724.Social and Economic Factors:The Advantages and Disadvantages of MultipleCropping Systems Compared to Sole-C
4、ropping or Monoculture Systems.73S.Yields of Corn,Beans,and Squash Planted in Polyculture as Compared to Lowand High Densities of Each Crop in Monoculture.746.Effects of Mixed and Row Intercropping on Yields and Nutrient Uptake ofCorn and Pigeon Peas in St.Augustine,Trinidad,Expressed as Relative Yi
5、eldTotals.767.Biomass Distribution of Dry Matter in a Corn/Bean Polyculture as Compared toa Corn Monoculture,in Tacotalpa,Tabasco,Mexico.768.Classification and Examples of Agroforestry Technologies.80FigureFigure No.Pagel.Distribution of the Relative Yield Totals of Mixtures Based on 572 PublishedEx
6、periments.72Chapter VMultiple Cropping Systems:A Basis for Developing anAlternative AgricultureThis paper presents a general discussion ofthe concept of multiple cropping,including adescription of the different types of systems,and the advantages and disadvantages of theirwidespread use,both biologi
7、cal and socio-economical.These systems are designed to in-tensify agricultural production both in termsof yields per unit area and through the moreefficient use of space and time.Examples of yield increases with multiplecropping systems are expressed in terms ofRelative Yield Totals(RYT)or Land Equi
8、valentUse(LER)where the production per unit areawith the multiple crops is greater than the sumof equivalent areas planted to monoculture.This increase in production is explained byhigher overall efficiency of resource use.Specific examples of the effects of multiplecropping systems on resource use,
9、conserva-tion,and management are discussed,Variablesconsidered include microclimate,light,soil,water,pests,diseases,weeds,crop interac-tions,space,and time.The special case ofagroforestry,which combines trees with cropsand grasses,is discussed.In conclusion,the socioeconomic implica-tions,both advan
10、tageous and disadvantageous,are discussed.Also,the great potential formultiple cropping systems in agriculture in theUnited States is presented.Research needs tobe directed to test these alternatives.Multiple cropping is not a new form of agri-cultural technology,but instead is an ancientmeans of in
11、tensive farming.Multiple croppinghas been practiced in many parts of the worldas a way to maximize land productivity in aspecific area in a growing season.Generally,the practice of planting two or more crops onthe same field is more common in tropical re-gions where more rainfall,higher tempera-ture
12、s,and longer growing seasons are morefavorable for continual crop production.Aspopulation has increased,increasing the needfor agricultural production,the use of multi-cropping systems is more prevalent.Thoughthe history of multiple cropping is old,the con-cept has received very little attention fro
13、m agri-cultural scientists,and what limited interest ex-ists has come about very recently.Why was this interest increased so dramat-ically in such a short time?Food shortages inmany parts of the world,as well as the threatof insufficient supplies in the near future,con-tinues to stimulate more inten
14、sive agriculturalinvestigation in a search for more productivealternatives.As a consequence,it appears that6970we are about to embark on a new phase of agri-cultural research.Exactly what form it will takeis still not known,but the reasons for this newapproach are rapidly becoming apparent.First,we
15、have begun to observe a leveling offin yield increases brought about by the typesof genetic manipulation that gave us such rapidand impressive yield increases during the“Green Revolution.”It is as if we have reacheda“yield plateau”with the current lines of re-search and crop selections.Large-scale u
16、se ofsingle varieties(e.g.,some of the InternationalRice Research Institute(IRRI)varieties of rice),with broad adaptability,produced major break-throughs in yields.But it appears that these va-rieties have almost reached their maximumyield potentials.In many areas with specificsoil and climatic cond
17、itions,they have not per-formed as well as hoped,especially on landmore difficult to mechanize or irrigate.Thuswe must begin to look for varieties with morespecific adaptability and selected for specificenvironments,or else consider alternativecropping systems.best agricultural landsareas with good
18、soiland easy water control.Future increases inproduction,therefore,will demand a new andinnovative way of managing these highly pro-ductive lands,as well as looking for methodsto make marginal lands increasingly produc-tive.Only 20 percent of Asia rice land,for ex-ample,is irrigated,and the new high
19、 yieldingrice varieties(which also require high levels offertilizers,water use,and pest control)have notpenetrated much beyond this boundary(16).The third factor is the oil crisis.Oil pricescontinue to soar,and with them,the cost offer-tilizers,pesticides,and fuel needed to build andrun farm equipme
20、nt and move irrigation water.Costs continue to mount for those inputs mostresponsible for achieving the dramatic yield in-creases of the“Green Revolution.”We arefaced with the necessity of having to considerother alternatives that might allow us to sub-stitute innovative biological or agronomic prac
21、-tices and varieties for these high cost inputs.Multiple cropping offers one of the most im-portant and promising of these alternatives.Second,most of the dramatic yield increasesduring the past few decades have been on theCONCEPTS AND DEFINITIONSMultiple cropping systems use managementpractices whe
22、re the total crop production froma single piece of land is achieved by growingsingle crops in close sequence,growing sev-eral crops simultaneously,or combining singleand mixed crops in some sequence.The mostimportant aspect of multiple cropping is theintensification of crop production into addi-tion
23、al dimensions.Multiple cropping includesthe dimensions of time and space;for exam-ple,when two crops share the same space atthe same time.A classification of types of multiple croppingsystems is presented in table 1.Note thatspecial emphasis is placed on the distinctionbetween intercropping,where tw
24、o or morecrops are grown at the same time,and sequen-tial cropping,where two or more crops aregrown on the same piece of land,but one fol-lowing the other.Some additional terms used in multiple crop-ping are presented in table 2.Agroforestry,asa particular type of intercropping system,willbe discuss
25、ed in some detail.Also,“mixed crop-ping,“polyculture,”and“multiple cropping”will be used interchangeably in this review.Bycombining different aspects of simultaneousand sequential cropping systems,it is possibleto visualize a truly complex pattern of differentmultiple cropping systems.This classific
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