Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available ...Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available N, P and K), acidification and salinization due to excessive input of fertilizers in greenhouses in Tianjin. The study showed that, in particular, soil available P content increased with the age of greenhouses. In contrast, our results did not reveal higher K accumulation and lowered pH in the greenhouse soils compared with cultivation in open fields. Over-fertilization, causing high NO 3 accumulation, most likely resulted in salinity problems in the greenhouses. Ninety percent of the investigated greenhouse soils had electrical conductivity values of saturated paste extracts of 2-10 d S m-1 , which might affect the yields of vegetable crops like green bean, pepper, cabbage, carrot, eggplant, lettuce, spinach, celery, cucumber and tomato. The findings of our survey of the current fertility and salinity problems in greenhouse soils suggest that there is an urgent need to improve the farmers' practices and strategies in fertilization management in greenhouses of China. Because education and the agricultural technical extension services may play a more important role in avoiding overuse of fertilizers, we suggest that current nutrient management practices should be improved in the near future through training of local farmers in farmers' schools and through strengthening the agricultural extension services with practical techniques.展开更多
For a Chinese dairy farm with 2200 milking cows,the annual manure production and manure nutrients(nitrogen and phosphorus)were estimated.Gaseous nitrogen losses from cattle housing with scraped solid floors were based...For a Chinese dairy farm with 2200 milking cows,the annual manure production and manure nutrients(nitrogen and phosphorus)were estimated.Gaseous nitrogen losses from cattle housing with scraped solid floors were based on on-farm measurements.Based on experiences from the Netherlands,nutrient levels in the solid and liquid fractions after slurry separation were estimated.On the basis of assumptions for nutrient losses during covered lagoon storage and land application of the liquid fraction,nitrogen and phosphorous fertilization rates were calculated for the 67 hm^(2)of agricultural land that receive the liquid fraction by gravity irrigation.The results show that the application rates of nitrogen and phosphorous significantly exceed the crop needs,which will probably result in losses to soil and water.In order to aim for a balance between nutrient application and crop needs and,as such,reduce environmental harm,the authors recommend to establish application standards for nitrogen and phosphorous on arable land in China and to formulate farm-specific Nutrient Management Plans.展开更多
基金Supported by the German Federal Ministry of Education and Research (BMBF) (No. 00330800A)
文摘Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available N, P and K), acidification and salinization due to excessive input of fertilizers in greenhouses in Tianjin. The study showed that, in particular, soil available P content increased with the age of greenhouses. In contrast, our results did not reveal higher K accumulation and lowered pH in the greenhouse soils compared with cultivation in open fields. Over-fertilization, causing high NO 3 accumulation, most likely resulted in salinity problems in the greenhouses. Ninety percent of the investigated greenhouse soils had electrical conductivity values of saturated paste extracts of 2-10 d S m-1 , which might affect the yields of vegetable crops like green bean, pepper, cabbage, carrot, eggplant, lettuce, spinach, celery, cucumber and tomato. The findings of our survey of the current fertility and salinity problems in greenhouse soils suggest that there is an urgent need to improve the farmers' practices and strategies in fertilization management in greenhouses of China. Because education and the agricultural technical extension services may play a more important role in avoiding overuse of fertilizers, we suggest that current nutrient management practices should be improved in the near future through training of local farmers in farmers' schools and through strengthening the agricultural extension services with practical techniques.
基金supported by the Ministry of Economic Affairs of the Netherlands through the TKI AF14247 Sino-Dutch Dairy Development Center(SDDDC)program(BO-27.04-001-014)the Beijing Municipal Science and Technology Plan Project(D151100005115001).
文摘For a Chinese dairy farm with 2200 milking cows,the annual manure production and manure nutrients(nitrogen and phosphorus)were estimated.Gaseous nitrogen losses from cattle housing with scraped solid floors were based on on-farm measurements.Based on experiences from the Netherlands,nutrient levels in the solid and liquid fractions after slurry separation were estimated.On the basis of assumptions for nutrient losses during covered lagoon storage and land application of the liquid fraction,nitrogen and phosphorous fertilization rates were calculated for the 67 hm^(2)of agricultural land that receive the liquid fraction by gravity irrigation.The results show that the application rates of nitrogen and phosphorous significantly exceed the crop needs,which will probably result in losses to soil and water.In order to aim for a balance between nutrient application and crop needs and,as such,reduce environmental harm,the authors recommend to establish application standards for nitrogen and phosphorous on arable land in China and to formulate farm-specific Nutrient Management Plans.
