Leaching loss of dissolved organic nitrogen from cropland ecosystems

Abstract

While widely studied in grassland and forest ecosystems, dissolved organic nitrogen (DON), an important form of N lost through leaching, has received little attention in cropland ecosystem research. A global literature review and partial least squares path modeling (PLS-PM) were adopted to assess the quantity and composition of N leaching loss under different cropping systems, soil types, and management practices, as well as to identify the major factors controlling DON leaching. Annual total dissolved nitrogen (TDN, organic + inorganic N) leaching under different cropping systems ranged from 4.0 to 383.2 kg N ha-1. Vegetable and rice production systems showed the greatest and least TDN leaching, respectively. Across different cropping systems, DON accounted for 4.7%–34.9% of TDN in leachate. The NH_4^+ N form of N leaching is negligible in most upland cropping systems (< 2.3%), but not so in lowland rice systems. The largest ratio of DON leaching to TDN leaching was found in a rice-wheat rotation (34.9%). Cropping systems in which animal manure or plant compost was applied or lowland rice was included showed a relatively high DON leaching ratio. Accordingly, in investigating DON leaching, more attention should be focused on cropping systems with manure application or lowland rice systems. Compared to climatic conditions and soil properties, field management practices (irrigation, chemical N input, and manure amendments) proved to be the factors most strongly influencing DON leaching. This suggests that optimizing water and N management practices is the most effective way of reducing the risk of DON leaching and increasing N use efficiency, particularly for vegetable and rice production systems.

Responses of functional genes involved in nitrogen cycling to green manuring in different paddy soils in south China

“…The introduction of legume green manure may change the soil environment, affect soil nutrients availability, and profoundly in uence N cycling process in the paddy soil due to the biological N xation (Lupwayi et al, 2016;Shari et al, 2014). The application of leguminous green manures in the rotation system increased the N retention in the soil and reduced the N loss by strengthening the connection between plants and soil microorganisms (Vries et al, 2012; Liang et al, 2021). The N released from green manure decomposition usually enters the soil microbial biomass N pool rst.…”

Responses of Functional Genes Involved In Nitrogen Cycling To Green Manuring In Different Paddy Soils In South China

“…The introduction of legume green manure may change the soil environment, affect soil nutrients availability, and profoundly in uence N cycling process in the paddy soil due to the biological N xation (Lupwayi et al, 2016;Shari et al, 2014). The application of leguminous green manures in the rotation system increased the N retention in the soil and reduced the N loss by strengthening the connection between plants and soil microorganisms (Vries et al, 2012;Liang et al, 2021). The N released from green manure decomposition usually enters the soil microbial biomass N pool rst.…”

The importance of introducing cover crops in conventional agriculture

“…Van Kessel et al (2009) point out that leaching of DON into stream and drinking water reservoirs causes eutrophication and can become a potential risk to human health. According to them and Liang et al (2020), cropping systems in which animal manure or urine was applied showed significant DON losses. Apart from the study of Salazar et al (2019), many other researchers explore the ability of cover crops to lower the amount of both DON and DIN (dissolved inorganic nitrogen) leaching (Salmerón et al 2011;Gabriel et al 2012).…”