作物系數(shù)計(jì)算方法

1、方法一：作物需水量/參考作物需水量1.作物需水量：（4）作物需水采用水量平衡方程計(jì)算：ET = /W + P + I + SG - DP式中：kt為作物生育期內(nèi)某時(shí)段的需水量，mm；為 時(shí)段內(nèi)土壤儲(chǔ)水量變化量為時(shí)段內(nèi)有效降雨量，mm； I為時(shí)段內(nèi)灌水量，mm ； SCr為時(shí)段內(nèi)地下水利用量，mm； DP 為時(shí)段內(nèi)深層滲漏量,mmo2 .參考作物蒸散量A aRn +0.26( ej(l +Cu2)P 7式中：P。和P分別為海平面標(biāo)準(zhǔn)大氣壓和計(jì)算地點(diǎn)的實(shí) 躍氣壓（hlW ； Rn為太陽凈輻射，（州心出為飽和水汽壓 -溫度曲線上的斜率（hP坎一）；邛為濕度計(jì)常數(shù) （hPnt T） 為空氣實(shí)際水汽壓（

2、hPa）;氣為飽和水汽壓 （hPa） ；u2為2 m高處風(fēng)速（mA） ;C為風(fēng)速修正系數(shù)口由我國(guó)氣象站常規(guī)高度的風(fēng)速測(cè)定值換算成2 m高處的風(fēng)速值時(shí)需 乘以0. 75的系數(shù)。為了考慮干熱空氣平流作用和溫度層結(jié)對(duì)風(fēng)速的 影響，需要對(duì)風(fēng)速進(jìn)行修正，其修正系數(shù)值C如表5所示。表5 Penman公式中的風(fēng)速修正系數(shù),月最高與最低平出J 月平均最依t溫.氣溫的溫差風(fēng)速修正系數(shù)cAT5X12t ST 5 留13 Y AT 14 氣：14T 5T15弋 iT160.540.610.680.750.820.89方法二：地下水埋深法地下水埋深對(duì)作物產(chǎn)量與水分利用效率的影響及作物系數(shù)變化，地下水J，2011，vo

3、l33： 20-23作物系數(shù)K匚是作物本身生物學(xué)特性的反映，它與作物 神類，品種、生育期、作物群體葉面積指數(shù)等因素有關(guān)， Kc二KT/KTO，式中符&意義同前分析結(jié)果表明，在地下水 埋深較淺條件下，作物系數(shù)與地下水埋深有密切的關(guān)系，可 用下式表示,= % + b0HKr. = a +式中，H為地下水埋深，血次八膈廣上廣為經(jīng)驗(yàn)系數(shù)根據(jù)試臆資料分析，彳導(dǎo)出的經(jīng)驗(yàn)系數(shù)也,輔次由力如表6所 示,作物系數(shù)度化過程及作物系數(shù)與地下水埋深的關(guān)系.見圖1。表6作物系數(shù)與地下水埋深的關(guān)系作物月經(jīng)驗(yàn)系數(shù)相關(guān)系數(shù)標(biāo)準(zhǔn)誤差履辿）心）V(R2)r100,6964-0.0858一0.96520.091110.7477-0

4、.076Q0.98810. 102120.73570.09260.95410,08710.5162-0. 01820.76000. 116冬小麥20.8129-0.05890,98680.06330,67670. 9004-0.31530.70290.09240.60141.1620-Q.35X1(J.7382Q. 12450.54571.1399-0. 32910.67580.06860.29660.3645-0.11300*69820.04760. 8929-0. 0716=0.93100 05870.60720.8968-0.30390.55740. 109五米80.30361.6040

5、-0.51630,69920. 12590. 494410018-0.31320.76320. 109100.59800.3055-0. 11610.75060.05()地下水埋深對(duì)作物產(chǎn)量與水分利用效率的影響及作物系數(shù)變化.pdf參考騰發(fā)量（ET。）用PenmanMonteith公式計(jì)算，冬小麥在拔節(jié)抽穗期的日蒸散量（E T）由大型蒸滲儀測(cè)量冬小麥拔節(jié)抽穗期作物系數(shù)的研究.PDF以Kcini、Kcmid、Kcend表示作物生長(zhǎng)發(fā)育初期、中期及成熟后的3個(gè) 作物系數(shù)值。（陜西楊凌，西北農(nóng)林科技大學(xué)教育部旱區(qū)農(nóng)業(yè)水土工程 重點(diǎn)實(shí)驗(yàn)室的灌溉試驗(yàn)站）分段單值平均作物系數(shù)法將作物系數(shù)的變化過程概化為幾

6、個(gè)階段，根據(jù)各階段葉面蒸騰和土面蒸劃分4個(gè)階段；雙值作物系數(shù)法將作物 系數(shù)分成兩部分分別算，一部分是反映作物葉面蒸騰的基本作物系 Kcb，另一部分是反映土面蒸發(fā)的系數(shù)Ke由實(shí)測(cè)數(shù)據(jù)概化的冬小麥各階段的單作物系數(shù)分別為：冬小麥：Kcini =0.55； Kcmid =1.25； Kcend =.76。雙作物系數(shù)調(diào)整后的基礎(chǔ)作物系數(shù)冬小麥為：Kcini =0-55； Kcmid =1.25；=079關(guān)中西部冬小麥作物系數(shù)的試驗(yàn)研究.PDF表】豪小去各生育階段作秋系牧io B11 fli H_油3月4月5月6月山西蓄常0.40( mm JTc(nun繇校比采數(shù)t璃蓄水強(qiáng)度（am AJ10 A1 13

7、 n福律-出碧10 1 23 日s“-砧10.60.酮1. 151. 32出荷-升麋11 JJ 13 H2127.0033. &3 2J& aL6I12 ft 2 U19a.?H. 12.2?星冬柬育2 月 15 H7S4Q-.94粕3頑0.52返青島身18日33*LW13*1 05艮31l.0起身,傳節(jié)4月e n2143. 50a. 31.1310.651494 月 NN H1435. 4441.349. 70LiO挑用-抽視4月站H722. 9232.51.426. 6E64抽棚-開花5726.014O51.56E. 245- 7B開m染$月的日H58. 59陽71.58IS. 876.6

8、3，用熟NE3日1443.找12. C1.M14. 65S. 34fi H 7 H417. 8223 01.294. 681 73全生育期237m.o*49L2L32IDD,g2. 07魯北地區(qū)主要作物不同生育期需水量和作物系數(shù)的試驗(yàn)研究.pdf袁三秸桿茂蓋栽培射誓小麥不同生育勘需水量和作物系敝的賑響頊目1生片期日期播神一越務(wù)200S- E2- 09越筌一起烏3009 -Q3-21起身一莪節(jié)3009 -&1 - 10攘節(jié)TlJjft 3009-04- 30荊植一肅爆潮漿一成熟2009 06-06全生甘期TK：天敷句50102X)301?22S&乍雨址FmniiH.3孔49.032 J55 A1

9、,9130 1噩底域/5000IW.0(1100.0200.0CT/npn48 9107.44.65B_3S5.18J-7402-?落地W水需EfltAnni49.5土郵直94_9上料職6上以4州隊(duì)12.2l.2x6.0K.0 11.8487.6 IU. 9 a A2成需水地巾40.0 30.478.4 38.0M.2 ：20.979.6 lh.4B6.2 t2.1K.0 25.0144.4123.5 L A1.01 . 340.3SiD.23J .200.3J.4DztD. 211.71 0.4J ,29t0.14.21 0.(6 a A覆桅水擔(dān)。，82女。.破D.73 0.35姻土。.盟1

10、.37i 0.28|8560.041 .27 + 0.301.10 0 .06 b A魯北地區(qū)秸桿覆蓋對(duì)冬小麥需水量、作物系數(shù)及水分利用效率的影響.pdf表3 3種方法計(jì)算的春小麥4個(gè)生長(zhǎng)階段的作物系敷值Table 3 Vslaes of crop coefficient derived frrm differtnt methods for spring wheat during four stages盼段 StagesFAOMonEihPenmanFAOBlaney-Criddk苗 期 Iriitial stagfe0.450,490.52營(yíng)養(yǎng)期 Development stage0.900

11、,890.95生殖.期 Repnxluuive slagel.II1.14U19成熟期 Maturity siage0.520.52Q.68平均 Average0.750.760.84春小麥奈曼地區(qū)位于內(nèi)蒙古東部，是我國(guó)北方農(nóng)牧交錯(cuò)帶沙漠化最嚴(yán)重的地區(qū)之一奈曼地區(qū)灌溉麥田蒸散量及作物系數(shù)的確定.pdf區(qū)域_小麥WheatRegionAV iniK 匚 micFKr end地中海 Mediterraneanu, 4h 150, 25, 0.4太行山前平原 The pied mom of Mi*Taihang。一 58L 360. 70T太行山山前平原作物系數(shù)與降水年型關(guān)系探討.pdf表1小麥竺剝

12、喝水堂酊“）檔考.壬少客箕星尤丁左作坳有0/0宇育時(shí)段起止IT期f/d時(shí) /mm日平均 .|ui*d_LX mriL日平卻47：. .innrd-1K返聲一起身如 12-151 L 91. ：35. 42, 40, 4S起4 一技肯禎 27-04-21G0 &2. S1 !土 93. 72族節(jié)一孕視luSti.SJ. 9餌3土 D0. 7(學(xué)甩一抽熊由理T 1U混S6頊47. ?乙31. 1JUS 1-f：F-i5cm &5. i25, ?5. ；1.珀升花一圳熟O54fi-06-Cfi24佻95.7122.5 11.眈乳制一成射而眼-瞞小&i打?, S35.9h. I；. 4：返肖一腐熟L春

13、片生育期）03-32Li明爪,.；3,9廈,4L 4L SS應(yīng)用時(shí)域反射儀測(cè)定作物需水量和作物系數(shù).pdf根據(jù)fRo推薦的修正公式（3）和（4）,結(jié)合陜西楊凌地區(qū)的 氣候條件及對(duì)比試驗(yàn)區(qū)蒸滲儀實(shí)測(cè)值,如品種無變化，修正后正 常供水條件下冬小麥的基礎(chǔ)作物系數(shù)為：及 =0, 25 ,K協(xié)瑚 1. 20 Ks =夏玉米的基礎(chǔ)作物系數(shù)為：Kg = ，25, Km = 1.26K*2= 0一 65,從構(gòu)建的雙作物系數(shù)曲線看，雙作物 系數(shù)在各階段都與實(shí)測(cè)值較符合，說明基礎(chǔ)作物系數(shù)反5和土壤 蒸發(fā)系數(shù)虬的確定方法是適合本地情況的見圖1（圖中尸卜表 示降雨和港溉，下同孔陜西楊凌的西北農(nóng)林科技大學(xué)灌溉試驗(yàn)站楊凌

14、地區(qū)冬小麥和夏玉米蒸發(fā)蒸騰和作物系數(shù)的確定.pdf*Penman-Monteith form of the combination equation(1948 Penman 公式改進(jìn))The Peninnn-Moiiteith form of the conibination equation is:(Rn - G) - pa % -XET =亍(3)A - Y 1 -where Rn is the net radiation, G is the soil heat flux, (es - ea) represents the vapour pressure deficit of the ai

15、r, pa is the mean air density at constant pressure, cp is the specific heat of the air, A represents the slope of the saturation vapour pressure temperature relationship, y is the psychrometric constant, and rs and ra are the (bulk) surface and aerodynamic resistances.In J m WW mu.wherelaaeroclviian

16、iic resistance s in1,Zmheight of wind measiireuients m.Zhlieiglit of linniidiry measurements in.dzero plane displacement lieiglit in,rouglmess leiigili governing monieiitimi transfer in,z血roughness lengrli goveniiiig transfer of heat and vapour in.kvon Karmans constant. 0.41 -.Lkwind speed at height

17、 z m s1.耳* = I aTactiver(bulk) surface resistance s tn1,nbulkresisJaiice of the wtU illiuiunated kaf |s uf1 tactive (sui山leaf area imkx m2 (leaf area m2 (soil surface),*FAO PENMAN-MONTEITH EQUATION (May 1990)By defining the reference crop as a hypothetical crop with an assumed height of 0.12m having

18、 a surface resistance of 70 s m-1and an albedo of 0.23, closely resembling the evaporation of an extension surface of green grass of uniform height, actively growing and adequately watered, the FAO Penman-Monteith method was developed. The method overcomes shortcomings of the previous FAO Penman met

19、hod and provides values more consistent with actual crop water use data worldwide.From the original Penman-Monteith equation (Equation 3) and the equations of the aerodynamic (Equation 4) and surface resistance (Equation 5), the FAO Penman-Monteith method to estimate ETo can be derived (Box 6):0.408

20、 A(R-G) - 丫電 & -)ET0T + 2BA - 丫(1 + 0.34叼)bereELRnGI112Ce印A7reterence evaporiaiispirafion itun day |, net radiation at the ciop surface MJ m2 day l, soil heat fhix density MJ m- day , mean daily air temperanire at 2 m height DCJ. wind speed at 2 m height m s1, saturation vapour pressure kPa actiud v

21、apour pressure kPa.satTiratiou vapour pressure deficit kPa, slope vapour pressure curve kPa C1, psychrometric constant kPn C1.* Kc & crop evapotranspiration (ETc)By using the FAO Penman-Monteith definition for ETo, one may calculate crop coefficients at research sites by relating the measured crop e

22、vapotranspiration (ETc) with the calculated ETo, i.e., Kc = ETc/ETo. In the crop coefficient approach, differences in the crop canopy and aerodynamic resistance relative to the hypothetical reference crop are accounted for within the crop coefficient. The Kc factor serves as an aggregation of the physical and physiological differences between crops and the reference definition.(ZEJ TE)洛pc-ra 節(jié)切_luoqJBFIGURE STypical presentation of the variation In the active grn) Leaf Area Index over the gi