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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. what can we learn from long-term paddy and vegetable field experiments for better nutrients management and less environmental impact in Taihu Lake region?. Ju MIN, Jun QIAO, Tingmei YAN, Xu ZHAO, Weiming SHI.
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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 what can we learn from long-term paddy and vegetable field experiments for better nutrients management and less environmental impact in Taihu Lake region? Ju MIN, Jun QIAO, Tingmei YAN, Xu ZHAO, Weiming SHI Institute of Soil Science Chinese Academy of Sciences Nanjing, China
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
TO evaluate fertilizer N impact on environment and balance of high yield and environmental cost, two long-term field experiments were conducted Experimental site: A typical rice-wheat rotaion fieldin Yixing, Jiangsu Province, the experiment starts 2008 (6y, 12 crop season) (another from 2003) Taihu Lake A typical greenhouse vegetable production farmin Yixing, Jiangsu Province,the experiment starts from 2005 (8y, 24 crop seasons)
1. Long-term paddy field experiments • Cropping system: Double crops: rice-wheat (from 2008 to 2013) rice-alfalfa (from 2010 to 2013) • Fertilizer treatments: 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.
2. Long-term greenhouse vegetable field experiments • 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) All treatments received 78 kg N /ha from animal manure in addition to 150 kg K2O/ha and 120 kg P2O5 /ha as basal fertilizer each season.
N fate in rice-wheat rotation (average of 6 years) Wheat Rice
Control measures: Optimizing N input The trends of rice yield and the yields after six years 50% N
The N runoff in different N rates of rice season under rice-wheat rotation 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
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.
The annual runoff in different N rates under Alfalfa-Rice rotation Compared to local farmers’ normal N usage, reducing fertilizer N input by 56% under Alfalfa-Rice rotation reduced total N runoff by 64%.
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)
Control measures: Optimizing N input The optical N input is 930 kg N/ha (manure + synthetic N: 234+696)
Optimizing nitrogen input to reduce nitrate leaching loss in greenhouse vegetable production (kg/ha) RNL: Reduced N leaching 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)
Control measures: Catch crop 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.
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. 2. In greenhouse vegetable cropping system: • 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.
研究进展 The next step--- 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) Taihu Lake
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