苜蓿用钾肥ppt课件

1、苜蓿钾营养苜蓿钾营养概要概要:植物发育植物发育Plant development诊断诊断Diagnosis 产量与质量产量与质量Yield and quality经济经济Economics 灌溉与记录收成灌溉与记录收成Irrigation and record yields阳离子竞争阳离子竞争Cation competition平衡营养平衡营养Balanced nutrition苜蓿消费 另外,加拿大苜蓿11百万英亩，1.4 ton/A U.S. $70亿/年, 2000-2003 USDA-NASS; Statistics Canada苜蓿根系发育 多数侧根第一年贴近于土壤外表，但随着作物的

2、生长，会发育更多、更深的侧根 苜蓿根际较深、根密度较低 营养运用提高根系生长，确保根系获取水分和营养的土壤范围更大。苜蓿根系形状种植后约2月 旱地旱地Dryland 浸透更深浸透更深Deeper penetration 少而长侧根少而长侧根 更多的二级分支更多的二级分支 灌溉地灌溉地Irrigated 较浅较浅Shallower 多而短侧根多而短侧根More but shorter laterals 较少的二级分支较少的二级分支Weaver, 1926 (NE)旱地灌溉地苜蓿根系形状种植后约3月 旱地旱地Dryland 根系更多丰富的分支根系更多丰富的分支 分支到达与主根一样深分支到达与主根一

3、样深度度 较浅的根系较浅的根系 灌溉地灌溉地Irrigated 较少的分支较少的分支 更大的根深度更大的根深度 主根占优势主根占优势旱地灌溉地Weaver, 1926 (NE)苜蓿根系形状第一年终了 旱地旱地Dryland 土壤中更多分支超越土壤中更多分支超越1英尺英尺 最深达最深达 5 英尺英尺 根向下延伸根向下延伸 灌溉地灌溉地Irrigated 土壤中更少的分支超越土壤中更少的分支超越1英尺英尺 最深达最深达 6 英尺多英尺多 根系有更多的侧根根系有更多的侧根旱地灌溉地Weaver, 1926 (NE)苜蓿根系形状第二年七月十日 旱地旱地Dryland 深度超越深度超越9英尺英尺. 根向

4、下延伸根向下延伸 横向延伸少横向延伸少 灌溉地灌溉地Irrigated 深度近深度近10英尺英尺. 横向延伸多横向延伸多灌溉地Weaver, 1926 (NE)旱地限制根系生长的要素降低营养吸收病害虫害温度酸度低氧排水不畅过量盐或钠营养缺乏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 施用量施用量表面410-6 296-121912-181618-241030-3611Recovery at the end of the growing season with K placed in the Spring at various depths in an establish

5、ed alfalfa standPeterson and Smith, 1973营养缺乏诊断 目测 测土 组织分析苜蓿缺钾病症：小白点或黄点首先出如今老叶子外缘缺钾苜蓿中度缺钾苜蓿中度缺钾苜蓿严重缺钾苜蓿严重缺钾苜蓿Typical K Concentrations(at optimum fertility) 植株近顶部茎秆含钾高 上下部叶子钾浓度类似 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生长阶段的植株部门K, % 以干物质为以干物质为基础基础茎: 贴近地面2%茎: 近顶部up to 6%叶子:1.8 - 2.2%根:1.1%开花早期收获牧草

6、Forage harvested at early bloom:1.8% to 2.5%蓓蕾-早期开花上部6in.Top 6 in. at bud to early bloom:2.0% to 3.5%Lanyon and Smith, 1985随着苜蓿成熟钾浓度降低Barton and Reid, 1977 (WV)Growth StageShoot K, %Soil Testing andPlant Analysis Soil Testing Verify that K levels are being maintained Soil pH 6.5 or higher for effici

7、ent N fixation Plant Analysis Usually sample the top 6 in. at harvest Indication of adequate K fertility: 2% indicates insufficient K for winter hardiness Optimum yields usually contain around 2.5% K Record yield of 10 tons/A (non-irrigated), K content of 3%K Deficiency Hurts More Than YieldAdequate

8、 K Improves:Plant persistenceNumber of shoots per plantShoot yieldDeficient K:Reduces root starch storageReduces protein concentration in rootResults in poor survival and slowshoot growthLi et al., 1997 (IN)K2O added, lb/AGrewal and Williams, 2002 (Australia)K Fertilization IncreasesNodule ActivityK

9、2O added, lb/AK Fertilization ImprovesHay QualityGrewal and Williams, 2002 (Australia)Plant counts taken in May as % of those previous SeptemberBailey, 1983 (MB)K Helps Reduce Winterkillin Alfalfa1001971197219731974197519761977020406080Stand density (%)100 lb K2O/yrNo KYearAlfalfa Responses to Kin M

10、ixed Stands Largest where soil K fertilitylevels are low Increases over the lifeof the stand Includes quality as wellas yield Increased proportion oflegume to grass more protein Increases in irrigated production010020030040034516171819Hay yield, tons/AFertilizer K2O, lb/AInitial soil test Kwas 35 pp

11、m (low)4-yr total1989199219901991Most Economic RateKlausner and Goyette, 1993 (NY)Response to K IncreasesOver Life of Stand456702004006002.02.53.00200400600198919901991Rock SpringsLandisvilleYield, tons/AForage K, %Fertilizer K2O, lb/AAlfalfa response to K at two sites Most Economic RateBeegle, 1992

12、 (PA)Initial soil test K rangedfrom 130 to 170 ppm Response to K IncreasesOver Life of StandBerg et al., 2003 (IN)Added K, lb K2O/AGreatestresponseoccurred in5th yearResponse to K IncreasesOver Life of Stand67890100 200 300 400 5002.02.53.03.5Yield, tons/AFertilizer K2O, lb/AForage K, %Most Economic

13、 Rate19851986Sheard et al., 1988 (ON)19851986Response increases after intensive management Alfalfa response to K under intensive 5-cut management Initial soil test K of 170 ppm in 1984, declined to 80 ppm in the unfertilized treatment by spring 1987Soil K Levels:Turn K Fertilizationinto ProfitExampl

14、e: Annual economic returnto K fertilizer use:Assuming $90 per ton of hay and K2O at $0.15 per pound (price ratio of 3 lb hayper lb of K2O)Soil test KcategoryYieldresponseK2O rateNet returntons/Alb/A$/AVery low1.2335 57.75 Low1.0260 51.00 High0.290 4.50 Economics ofK FertilizationThe most economic ra

15、te of K fertilization changes as the ratio of K prices to hay prices changesSoil Test KPrice RatioCategory2345Most economic rate of K2O (lb/A)Very low425335270220Low330260214175High130906040Profitability:Short vs. Long-TermThe yield increase in response to K application gets larger as the alfalfa st

16、and agesBurmester et al., 1991 (AL)K2O application rate, lb/AAlfalfa stand density, plants/ft2K Fertilization According toSoil Test RecommendationMaintains Alfalfa StandsRecommended K rateFollet and Wilkinson, 199501234.555.566.57Soil pHYield, tons/A苜蓿产量受土壤PH影响Walworth and Sumner, 1990 (GA)石灰中和酸性土壤改

17、善苜蓿生长并提高营养恢复Yr 1Yr 1Yr 1Yr 2Yr 2Yr 2Yr 3Yr 3Yr 3pH 5.3pH 6.1pH 4.7Alfalfa yield, ton/A1公顷=15亩 1英亩=6亩 1公顷=2.5英亩1英镑=0.45公斤 1b/A=0.45kg/6mu=0.075推导出下表中系数为0.07521001b/A=157.5kg/mu 34001b/A=255 kg/muLiming Acid Soil Improves Alfalfa Growth and NutrientRecoveryWalworth and Sumner, 1990 (GA)苜蓿发芽组成Alfalfa s

18、hoot compositionHow Does this Changewith Irrigation?Record Yield:Researchers at University of Arizona(Yuma) set record for alfalfa yieldin a year:24.1 tons/A alfalfa hay in10 cuttings Optimal and uniform irrigation Chopped hay removed immediately after cutting N fertilizer regularly added was it nee

19、ded? 460 lb P2O5/A added before planting K management unknownCumulative Hay Yield, TonsK2O rate, lb/A0200400600600Optimum K Rate in Irrigated Alfalfa: An ExampleKoenig, 2002 (UT)Best economic returnToo much in one applicationPlacement and Application Options Establishment Broadcast to build up soil

20、test K before seeding Banded starters should contain mostly P Maintenance Apply following harvest to replace removal High rates: split over several cuts to avoid salt injury To boost winter hardiness, apply before critical fall growth period (before last 6 weeks of growth) When soil K levels are hig

21、h, spring applications can lead to higher K levels than desired, and may be unnecessary Yield response to K found in last harvest of 2000 For first harvest of 2001, no response to K fertilization was observed Reason:K can be released from soil minerals during winter and spring Volenec, 2002 (IN)K Im

22、pacts Fall Harvestmore than SpringFall Harvest, 2000K applied, lb K2O/A)Spring Harvest, 2001K applied, lb K2O/AManure Management Manure supplies many nutrients but usually not in the ratio requiredfor alfalfa! Physical problems compaction, crown damage,leaf burn, salinity Nutritional problems N can

23、stimulate weeds excessive K can cause cation imbalance in dairy feed rationsLuxury Uptake of K forDairy Feed K in alfalfa varies from3% Luxury uptake when soil Kis very high K levels above 3% unnecessary Liquid manure systems efficientlyrecycle K High K forage: A concern fordry dairy cows Leads to m

24、ilk fever, retained placentas after calving For the transition period (2 to 4 weeks before calving) forage with 2% K desired; dietary K should be 1.2% Corn silage, grains, distillers grains are low K feeds Anionic salts (chlorides or sulfates of NH4+, Mg, or Ca) can help correct the problemBurmester

25、 et al., 1991 (AL)K applied, lb K2O/ATissue Mg, %Magnesium Concentrations in AlfalfaK Competes with Other Cations for Plant Uptake: MgK applied, lb K2O/ATissue Ca, %Calcium Concentrations in AlfalfaK Competes with Other Cations for Plant Uptake: CaBurmester et al., 1991 (AL)K Fertilization ReducesUptake of Othe