1. what can we learn from long-term paddy and vegetable field experiments for better nutrients management and less environmental impact in Taihu Lake region? Institute of Soil Science Chinese Academy of Sciences Nanjing, China Ju MIN, Jun QIAO, Tingmei YAN, Xu ZHAO, Weiming SHI 中英养分管理和水资源保护学术研讨会 China-UK nutrient management and water resource protection workshop

2. N Runoff Leaching  To obtain high yield, large amount of fertilizer N is applied in China.  Consequently, considerable amount of N enters the environment through volatilization, runoff and leaching. This threat to environment is more serious in the Taihu Lake region. volatilization

3. A typical rice-wheat rotaion field in Yixing, Jiangsu Province, the experiment starts 2008 (6y, 12 crop season) (another from 2003) Experimental site ： Taihu Lake TO evaluate fertilizer N impact on environment and balance of high yield and environmental cost, two long-term field experiments were conducted A typical greenhouse vegetable production farm in Yixing, Jiangsu Province, the experiment starts from 2005 (8y, 24 crop seasons)

4.  Cropping system: Double crops: rice-wheat (from 2008 to 2013) rice-alfalfa (from 2010 to 2013)  Fertilizer treatments ： 1. Long-term paddy field experiments N rates (kg N/ha) Rice-wheat rotation 100%N90%N80%N70%N50%N30%NCK Rice270243216189135810 Wheat240216192168120720 Rice-alfalfa rotation 100%N55%N44%N33%N22%N11%NCK Rice2701501209060300 Alfalfa (Provided to the soil) 90.5±8.392.1±8.486.7±12.588.3±7.387.8±7.384.6±7.379.7±7.5 All treatments received 81 kg K/ha and 81 kg P/ha in rice season and 96 kg K/ha and 96 kg P/ha in wheat season as basal fertilizer.

5.  Cropping system: Triple crops: Tomato-Cucumber-Celery (from 2006 to 2009) Tomato- Lettuce -Celery (from 2010 to now)  Fertilizer treatments ： N rates (kg N/ha) TreatmentTomatoCucumber / LettuceCelery 100%N (traditional synthetic N rate) 300270300 80%N240216240 60%N180163180 40%N120108120 CK(no synthetic N)000 All treatments received 78 kg N /ha from animal manure in addition to 150 kg K 2 O/ha and 120 kg P 2 O 5 /ha as basal fertilizer each season. 2. Long-term greenhouse vegetable field experiments

6. Rice Wheat N fate in rice-wheat rotation (average of 6 years)

7. The trends of rice yield and the yields after six years 50% N Control measures: Optimizing N input

8. The N runoff in different N rates of rice season under rice-wheat rotation Wheat-rice rotation Run off in rice season (kg N/ha) 20082009201020112012Average CK7.34±0.9212.37±3.484.59±0.832.2±0.46.6±1.76.6 30%NN/A 4.7±0.79.5±2.27.2 50%N8.8±1.526.6±3.012.1±2.58.5±0.910.4±2.113.3 70%N10.1±2.035.8±7.816.3±2.69.6±0.813.9±2.417.2 80%N12.2±1.843.7±6.918.8±2.710.1±2.915.1±2.620.0 90%N13.0±2.137.7±3.220.7±2.811.6±4.215.1±2.319.7 100%N15.2±2.557.5±5.222.3±3.213.2±4.819.4±3.625.6 By decreasing traditional rate of synthetic N fertilizer by 30% run off was reduced by 33% without any yield loss in rice season under rice-wheat rotation

9. Alfalfa-Rice rotation Rice yield (kg/ha) 2010201120122013Average CK4789±1796275±2345414±905594±3715518 11%N5034±906306±895766±2616262±1155842 22%N5478±3346901±3746572±10746670±1296407 33%N5794±3577088±4826887±6417201±1676742 44%N5942±807412±2007411±6417399±1607041 55%N5879±1747296±1847725±1997264±6567041 100%N6735±2087084±6658778±5587317±4777479 Control measures： Optimizing N input and Alfalfa- Rice rotation When alfalfa incorporated into rice cropping system, decreasing traditional rate of synthetic N fertilizer by 56% ( 44%N ) will not lead any yield loss in rice season.

10. Alfalfa-Rice rotation Annual runoff (kg N/ha) 201020112012Average CK5.96±1.141.83±0.376.02±0.884.60 11%N6.99±1.441.90±0.186.18±1.025.02 22%N9.54±1.222.27±0.126.50±0.816.10 33%N11.26±0.633.67±1.206.75±0.977.23 44%N16.02±1.436.08±1.357.12±1.159.74 55%N18.50±2.266.99±2.067.96±0.9211.15 100%N29.88±3.2820.78±4.2631.41±6.5227.36 Compared to local farmers’ normal N usage, reducing fertilizer N input by 56% under Alfalfa-Rice rotation reduced total N runoff by 64%. The annual runoff in different N rates under Alfalfa-Rice rotation

11. N fate under the greenhouse vegetable cropping system in Taihu Lake region. (Min, et al. Pedosphere, 2011; Min, et al. Soil Use and Management, 2012)

13. Control measures: Optimizing N input The optical N input is 930 kg N/ha (manure + synthetic N: 234+696)

14. （ kg/ha ） By decreasing traditional rate of synthetic N fertilizer by 40% leaching loss was reduced by 39% without any yield loss in intensive greenhouse vegetable production systems. (Min, et al. Agricultural Water Management, 2011) Optimizing nitrogen input to reduce nitrate leaching loss in greenhouse vegetable production RNL: Reduced N leaching Treatment 2007200820092010201120126 Y average R N LYieldR N LYieldR N LYieldR N LYieldR N LYieldR N LYieldR N LYield N870 （ farmer ） --210--183--149--165--141--126--162 N696 （ -20% ） 38197351951915631174591594617038175 N522 （ -40% ） 682025917961156851651481629415886170 N348 （ -60% ） 1111598313085128110133178125204141129136

15. The effect of catch crop on the amount of total N leached (kg/ ha) and the relative total N captured by the catch crop in 2008 and 2009 (Min, et al. Nutr Cycl Agroecosyst, 2011) Compared to local farmers’ normal N usage, reducing fertilizer N input by 20 and 40% with a sweet corn catch crop reduced total N leaching by 50 and 73%, respectively. Control measures: Catch crop

16. Conclusions 1. In rice cropping system:  Optimal N input is 190 kg N/ha in rice season under rice-wheat rotation.  3% and 12% N were lost by runoff and leaching under farmer’s N input level.  By decreasing traditional rate of synthetic N fertilizer by 30% run off was reduced by 33% without any yield loss in rice season under rice-wheat rotation.  By decreasing traditional rate of synthetic N fertilizer by 56%( 44%N ) under Alfalfa-Rice rotation reduced total N runoff by 64% and also maintain the rice yields.  Optimal N input is 930 kg N/ha for vegetables.  3% and 20% N were lost by runoff and leaching under farmer’s N input level.  By decreasing traditional rate of synthetic N fertilizer by 40%, leaching loss was reduced by 39% without any yield loss;  Compared to local farmers’ normal N usage, reducing fertilizer N input by 20 and 40% with a sweet corn catch crop, this reduction could reach to 50 and 73%, respectively. 2. In greenhouse vegetable cropping system:

17. 研究进展 Long-term rice-vegetable rotation experiments was started in 2013 in this region.  Cropping system: Rice-vegetable rotation: Cabbage-rice-brassica chinensis CK: Cabbage-kidney bean-radish-brassica chinensis  Fertilizer treatments ： 1) 100%N (traditional synthetic N rate) 2) 70% N 3) 40%N 4) CK (no synthetic N) The next step--- Taihu Lake

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