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1、苜蓿钾养分苜蓿钾养分概要:植物发育Plantdevelopment诊断Diagnosis产量与质量Yieldandquality经济Economics灌溉与记录收成Irrigationandrecordyields阳离子竞争Cationcompetition平衡营养Balancednutrition苜蓿生产另外,加拿大苜蓿11百万英亩，1.4ton/AU.S.$70亿/年,2000-2003USDA-NASS;StatisticsCanada苜蓿根系发育多数侧根第一年贴近于土壤表面，但随着作物的生
2、长，会发育更多、更深的侧根苜蓿根际较深、根密度较低养分应用提高根系生长，确保根系获取水分和养分的土壤范围更大。苜蓿根系形态（种植后约2月）旱地Dryland渗透更深Deeperpenetration少而长侧根更多的二级分支灌溉地Irrigated较浅Shallower多而短侧根Morebutshorterlaterals较少的二级分支Weaver,1926(NE)旱地灌溉地苜蓿根系形态（种植后约3月）旱地Dryland根系更多丰富的分支分支达到与主根相同深度较浅的根系灌溉地Irrigated较少的
3、分支更大的根深度主根占优势旱地灌溉地Weaver,1926(NE)苜蓿根系形态（第一年结束）旱地Dryland土壤中更多分支超过1英尺最深达5英尺根向下延伸灌溉地Irrigated土壤中更少的分支超过1英尺最深达6英尺多根系有更多的侧根旱地灌溉地Weaver,1926(NE)苜蓿根系形态（第二年七月十日）旱地Dryland深度超过9英尺.根向下延伸横向延伸少灌溉地Irrigated深度近10英尺.横向延伸多灌溉地Weaver,1926(NE)旱地限制根系生长的因素降低养分吸收病害虫害温度酸度低氧排
4、水不畅过量盐或钠营养不足根瘤少土壤压实不同土壤深度的K回收率深度,英寸回收率,%of施用量表面410-6296-121912-181618-241030-3611RecoveryattheendofthegrowingseasonwithKplacedintheSpringatvariousdepthsinanestablishedalfalfastandPetersonandSmith,1973养分缺乏诊断目测测土组织分析苜蓿缺钾症状：小白点或黄点首先出现在老叶子外缘缺钾苜蓿中度缺钾苜蓿严重缺钾
5、苜蓿TypicalKConcentrations(atoptimumfertility)植株近顶部茎秆含钾高上下部叶子钾浓度相似根系含钾较少含2.5%钾的牧草相当于每收获吨重干物质除掉60英镑K2O生长阶段的植株部门K,%以干物质为基础茎:贴近地面2%茎:近顶部upto6%叶子:1.8-2.2%根:1.1%开花早期收获牧草Forageharvestedatearlybloom:1.8%to2.5%蓓蕾-早期开花上部6in.Top6in.atbudtoearlybloom:2.0%to3.5%Lan
6、yonandSmith,1985随着苜蓿成熟钾浓度降低BartonandReid,1977(WV)GrowthStageShootK,%SoilTestingandPlantAnalysisSoilTestingVerifythatKlevelsarebeingmaintainedSoilpH6.5orhigherforefficientNfixationPlantAnalysisUsuallysamplethetop6in.atharvestIndicationofadequateKfertil
7、ity:<2%indicatesinsufficientKforwinterhardinessOptimumyieldsusuallycontainaround2.5%KRecordyieldof10tons/A(non-irrigated),Kcontentof3%KDeficiencyHurtsMoreThanYieldAdequateKImproves:PlantpersistenceNumberofshootsperplantShootyieldDeficientK:Reducesroot
8、starchstorageReducesproteinconcentrationinrootResultsinpoorsurvivalandslowshootgrowthLietal.,1997(IN)K2Oadded,lb/AGrewalandWilliams,2002(Australia)KFertilizationIncreasesNoduleActivityK2Oadded,lb/AKFertilizationImprovesHayQualityGrewalandWilli
