K fertilizer demand in China

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1 Fertilizer K demand in China Zhang Fusuo, Chen Xinping, Cheng Linlin, Zhang Weifeng Department of Plant Nutrition China Agricultural University Zhangfs@cau.edu.cn

2 Outline K utilization in China K demand in China Discussion

3 K consumption in the world from 1961 to 2003 K Consumption(million North America West Europe China 30% Year (Data source: and )

4 K consumption in China from 1961 to Amount of K (million t) Cosumption of K Percentage of K in NPK (%) % Our goal is 18% Reasonable ratio for N:P:K=1:0.4:0.3 (li Jiakang, 2001) Year (Data source: and )

5 K balance in China from 1956 to K balance(million t) Year

6 Where did K go in China?

7 Changes on K distribution in different period (kg/ha) 1985 > ~150 50~100 20~50 <20 No data > ~150 50~100 20~50 <20 No data > ~150 50~100 20~50 <20 No data

K balance in 1985 Percentage (%) 40 35 30 25 20 15 10 5 0 <

8 K balance in 1985 Percentage (%) < >200 K balance(kg/ha)

9 K balance in 1996 Percentage (%) < >200 K balance (kg/ha)

K balance in 2002 Percentage (%) 60 50 40 30 20 10 0 <

10 K balance in 2002 Percentage (%) < >200 K balance (kg/ha)

11 Summary Q: Is it reasonable for K varied in areas? Does the negative balance means we must increase K input? How much K is demanded in China?

12 K utilization status in China K demand in China Discussion

13 1. Calculated by growth rate S=(1+X) n P S: K demand after n years P: K consumption in starting year X: growth rate of last several years P:1996 K consumption = 3650 thousand t n1 = 10 n2 = 15 X = 0.6 S2005 = 6540 thousand t S2010 = 8740 thousand t (Duan Shengqin, 2001) Shortcoming : Great uncertainties would came from The starting Year, n, and the growth rate which always affected by policy in China

14 2. Calculated by the ratio of N:P:K In 2000, Total fertilizer = N:P:K = 1: :0.25 In 2010, Total fertilizer = N:P:K = 1: :0.30 K demand in 2000 : thousand t K demand in 2010 : thousand t (Xie Jianchang, 1999) Shortcoming: N:P:K is uncertainty; too much fertilizer N was used in China

15 (1). N:K is uncertainty Wheat: average N:K=1:0.77 max N:K=1:2.03 min N:K=1:0.33 ( n= 7 ) Maize: average N:K=1:0.95 max N:K=1:2.26 min N:K=1:0.25 ( n= 9 ) Rice : average N:K=1:0.66 max N:K=1:1.2 min N:K=1:0.29 ( n= 6 ) (2). N fertilizer input in China is excessive: Investigation in North China Plain crop Optimized N input Farmers practice Percentage of excessive farmer % Winter wheat Summer maize

16 3. Calculated by experts recommendation K demand = Planting area* K recommendation per area of different crops crop recommendation area K demand crop recommendation area K demand (Kg/ha) (10 6 ha) (10 3 t) (Kg/ha) (10 6 ha) (10 3 t) rice cotton wheat maize sugarcane tobacco legume tea Sweet potato peanut rape fruit vegetable sum (Xu Xiucheng, 2006) Shortage : K recommendation is different due to different K soil level

17 Crop: rice wheat maize cotton The methods to calculate K demand K recommendation in different soil area percentage of different soil planting area tobacco tea North : planting area K recommendation in North South : planting area K recommendation in South Others: fruit vegetable planting area* K recommendation

18 K soil level index and different K level soil area percent Shangdong K soil level index percent soil area with different K level K soil level Soil test K (mg/kg) Very high High >120 90~120 % N= Medium 50~ > <50 Low <50 Soil test K (mg/kg) (Source:field experiments in Shandong,2006)

19 Jilin K soil level index percent soil area with different K level K soil level High Medium Soil test K (mg/kg) > % N= Low <100 > <100 Soil test K (mg/kg) (Source:field experiments in Jilin,2006)

20 Anhui K soil level index percent soil area with different K level Paddy field K soil level High Medium Soil test K (mg/kg) > % N= Low < > <50 Soil test K (mg/kg) Dry land K soil level High Medium Low Soil test K (mg/kg) > <60 % N= > <60 Soil test K (mg/kg) (Source:field experiments in Anhui,2006)

21 K demand in China in 2010 crop K demand(thousand t) crop K demand(thousand t) rice 2411 sugar cane 304 maize 1070 tea 118 wheat 1163 rape 873 sweet potato 428 tobacco 363 potato 167 fruit 2781 legume 677 vegetable 4118 cotton 434 sum 14908

22 Surplus K fertilizer in vegetables K (million t) output 2.54 million t input The K demand of vegetable will not always be so much!

23 K utilization status in China K demand in China Discussion

24 Discussion 1 Singh and Brar, noted that, in the soils of the Punjab, India's continuous cropping without K applications decreased the content of available K from 166 to 85 kg/ha. Despite this, there was no response to applied K because 90% of the K demand of the crop was met by K release from the Kf pool. (MUKHOPADHYAY & DATTA 2001) The release of K from non-exchangeable forms contributes substantially towards potassium uptake by the crops suggesting thereby that in these soils NH4OAc-extractable K may not be a good indicator of soil K fertility status.(d.k. Benbi et al)

25 Subsoil K in nutrition A substantial amount of K taken up by the plants must have originated from the subsoil or from the originally nonexchangeable K source. (A. Subba Rao et al)

26 Negative K balance is allowed in high K fertility soil Very high High Medium Target value Low Very low In soils with a good supply of available K(>166 p.p.m.), no K fertilization was necessary until the amounts reached the medium level. (Vasiliauskiene,1996)

27 Different K inputs in K balance 6 5 K(million t) % 10% Year Fertilizer K Residue K Straw ashes K Animal or human manure K Seed cakes K

28 Discussion 2 We need a large amount of data to get more accurate forecast for K demand Kex<100mg/kg area percent (

29 K demand in high yield Summer Maize: 7.0 Actual yield: 6t Yield (t) HP CP HP : y = -6E-05x x CP : y = 4E-06x x Yield potential: 12t. K demand: yield 6.5 t: 75kg/ha yield 8 t.: 171kg/ha K application (K2O,kg/ha) (IPI summer maize experiments in Hebei,2005)

Hybrid maize Yield t/ha <9 9-12 >12 K Uptake

30 Hybrid maize Yield t/ha < >12 K Uptake kg/ha (source:36 literatures)

31 Acknowledgments Data support by Key Project from Ministry of Agriculture(MOA) 2.Soil Testing and Fertilizer Recommendation from Ministry of griculture(moa) 3.The Recommendation And Evaluation Of K Fertilizer Application For The High Yield Crops In China from International Potassium Institute( IPI) Thank Sun Yixiang and Meng Qingfeng for data collection!

32 Thanks for your attention!

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..._-200701002 營養障礙症 Nutritional disorders ăധ ͻğnitrogen deficiencyğ 三起因 1.施用未腐熟的有機物因其中之碳氮比過作物吸收氨或硝酸態氮素後由光合作用合成之碳水化合物經氧化作用產生能量供給氮素合成氨基酸再由氨基酸合成蛋白質為維持生命的重要化合物 (4) 高易造成氮的缺乏 2.粗質地的土壤稻田保肥力差施用之氮肥易流失 3.氮肥施用量不足