Effects of straw returning and nitrogen addition on soil quality and
physicochemical characteristics of coastal saline soil: A field study of
4 consecutive wheat-maize cycles
Abstract
The effects of different straw returning and nitrogen addition levels on
soil quality are important for proper coastal saline soil remediation.
Two maize/wheat straw returning levels (1.0 × 10 4 kg
ha -1 (2S) and 5.0 × 10 3 kg ha
-1 (S)) and three inorganic nitrogen addition levels
(300 kg ha -1 (N2), 150 kg ha -1 (N)
and 75 kg ha -1 (N1/2))—were studied, with 150 kg ha
-1 inorganic nitrogen and without straw addition
treatment as the control (CK), to elucidate the response of soil
physical and chemical properties to the two factors. Dry-sieving
technique was applied to fractionate the soils into silt-plus-clay
particles (< 0.053 mm, CS), microaggregates (0.053–0.25 mm,
MI), small macroaggregates (0.25–2.0 mm, SM), and large macroaggregates
(> 2 mm, LM). After four consecutive wheat-maize cycles,
different straw and N fertilizer treatments obviously decreased the
salinity contents, increased the total nutrient contents, and optimized
the soil structure of the saline soil. The saline soil reclamation
effects showed significant distinctions among the different straw and N
fertilizer treatments. The 2SN2 treatment displayed the greatest effects
in regard to decreasing salinity, increasing the total soil nutrient
contents and optimizing the soil structure, which resulted in the best
remediation effect. Straw returning play a major role in decreasing soil
salinity and enhancing saline soil aggregate formation. N fertilizer
addition supplies rich nutrients for straw decomposition, and promotes
soil microbial growth and reproduction, which brought about C
sequestration in coastal saline soil. During the coastal saline soil
remediation process in the Yellow River Delta, it is suggested to
prioritize straw returning and moderate N fertilizer addition, and live
together with moderate P fertilizer application.