Abstract
Overuse of chemical fertilizer and/or manure in agriculture is a principal factor in water eutrophication in China. Our previous study indicated that reducing chemical fertilizer input effectively decreased the soil nitrogen, phosphorus, and potassium in an intensive vegetable cropping system in the coastal area of southeast Lake Dianchi, China. This study aimed to decrease the input–output balance, namely the nutrient balance between input of fertilizer and output through vegetable harvesting, by reducing chemical fertilizer application without yield loss. A pot experiment was performed using chemical fertilizer with different amounts of N, P, and K on soils from six vegetable fields’ representative of the study area. High nitrate concentration in soils 2, 3, and 6 resulted in high N absorption from soil, and low N absorption from chemical fertilizer. Moreover, the responses of dry matter production to N absorbed from chemical fertilizer were less sensitive in soils 2, 3, and 6 than those in the other soils. Accordingly, reducing N input of chemical fertilizer did not decrease total N absorption or dry matter production, which should be the reason why reducing N input of chemical fertilizer did not reduce dry matter production in soils 2, 3, and 6. In the cases of soils 1, 4, and 5, reducing N input of chemical fertilizer reduced dry matter production, owing to lower levels of soil nitrate. This study should be helpful for reducing nutrient surplus from chemical fertilizer in the coastal area of southeast Lake Dianchi and other eutrophic agricultural areas in China.
Highlights
Over the past three decades, multiple cropping has played a very important role in meeting the rising need for food in China (Yan et al, 2014); chemical fertilizer consumption has increased greatly in this intensive cropping system (Ju et al, 2007)
Ju et al (2006) reported that nitrogen (N), phosphorus (P), and potassium (K) surpluses to greenhouses were more to wheat–maize fields and apple orchards on the north China plain; Chen et al (2004) evaluated the effect of fertilizer practices on nutrients accumulation in vegetable fields in the Beijing region; Min et al (2011) determined the N balance and loss in greenhouse in southeastern China; and Moritsuka et al (2013) reported that accumulation of soluble nutrients in soil was due to over-application of fertilizers in the southeastern basin of Lake Dianchi, China
− N, P, or K output by vegetable The N, P, and K absorbed from sources other than chemical fertilizer was defined as N, P, and K outputs under application by N0-P100-K100, N100-P0-K100, and N100P100-K0, respectively
Summary
Over the past three decades, multiple cropping has played a very important role in meeting the rising need for food in China (Yan et al, 2014); chemical fertilizer consumption has increased greatly in this intensive cropping system (Ju et al, 2007). Calculation of the nutrient input−output balance, namely subtracting the nutrient output through crop harvesting from the nutrient input of fertilizer application, was thought to be one useful method for estimating nutrient surpluses in many studies (He et al, 2007; Ju et al, 2006; Phupaibul et al, 2002). Decreasing nutrient input–output balance means reducing fertilizer application or enhancing output through crop harvesting, which should reduce nutrient surpluses. Most of former studies only calculated the nutrient input−output balance; whereas, few of them introduced practical measures to reduce nutrient surpluses by decreasing the input–output balance in vegetable fields under intensive cropping. This study aimed to decrease agricultural pollution by reducing input of chemical fertilizer according to soil characteristics while maintaining vegetable yield.
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