Abstract
Sewage sludge and green manure have become widely used organic amendments to croplands in many regions of the world. However, the amending effect of the combination of sewage sludge with green manuring in reclaimed coastal mudflat salt-soil has been unclear yet. This paper was one of earlier studies to investigate and evaluate the effects of sewage sludge amendment combined with green manuring on selected soil physicochemical properties of the mudflat soil in a rain-fed agroecosystem. The mudflat salt-soil was amended by one-time input of sewage sludge at the rates of 0, 30, 75, 150, and 300 t ha−1. After green manuring for three consecutive seasons, maize (Zea maysL.) was planted in 2013 and 2014. The results showed that SSA combined with green manuring decreased bulk density, pH, salinity, and exchangeable sodium percentage of the topsoil (0–20 cm soil layer) and increased aggregate stability, cation exchange capacity, and N and P concentration of the topsoil. As a result, the maize yield increased with the increase of SSA rates. Sewage sludge combined with green manuring can be applied in coastal mudflat salt-soil amendment, which provides an innovative way to create arable land resources and safe disposal of sewage sludge.
Highlights
Soil salinity is a major obstacle in the potential utilization of land resources in salt-affected areas
Under the influence of different sewage sludge amendment combined with green manuring, the percentage of aggregates of different size classes significantly varied in the topsoil (0–20 cm) and subsurface (20–40 cm) layers
The percentage of >0.25 mm water-stable aggregates in the topsoil increased by 7.5–25.1%, 29.7–96.1%, 105.5–121.6%, and 143.5–247.7% at 30, 75, 150, and 300 t ha−1 sewage sludge amendment (SSA) rates in 2013 and 2014, respectively, compared to the control soil
Summary
Soil salinity is a major obstacle in the potential utilization of land resources in salt-affected areas. The newly reclaimed coastal mudflats, as typical salt-soil, have high salinity, high pH, and macronutrient deficiencies [5]. High salinity of mudflat salt-soil is driven by the strong evaporation demand of the air, shallow salt solution rise to the soil surface through soil capillary in the dry season [6]. In the area rich in freshwater resources, soil salinity reduction is often accomplished through freshwater irrigation [7]. Faced with the scarcity of freshwater resources, organic matter amendment is an effective alternative to decrease soil salinity by forming soil aggregates and breaking capillary rise in saltsoil reclaimed from coastal mudflats in the eastern area of China [8, 9]
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