Coastal saline soil aggregate formation and salt distribution are affected by straw and nitrogen application: A 4-year field study

Abstract Little is known about the effects of straw incorporation on saline soil aggregate formation or salt distribution in coastal zones. In this study, a 4-year coastal wheat/maize rotation field experiment was employed. In each growing season, maize/wheat straw was applied at the rates of 5.0 × 103 kg ha−1 (S) and 1.0 × 104 kg ha−1 (2S), and inorganic N was applied at the rates of 75 kg ha−1 (N1/2), 150 kg ha−1 (N), and 300 kg ha−1 (N2). Treatment without straw addition and applied with 150 kg ha−1 inorganic N was used as the control (CK). Dry- and wet-sieving techniques were used to fractionate the soils into large macroaggregates (> 2 mm, LM), small macroaggregates (0.25–2.0 mm, SM), microaggregates (0.053–0.25 mm, MI), and silt-plus-clay particles ( 0.25 mm, LA + SA) ranged from 74.2 %–88.3 % and 28.4 %–37.6 % in straw applied treatments, which significantly increased by 14.7 %–19.0 % and 21.1 %–32.4 % compared to CK, respectively (p