Effects of straw mulch and buried straw on soil moisture and salinity in relation to sunflower growth and yield

Abstract

Salt accumulation in the root zone can be controlled by reducing the upward movement of salts and evaporation in arid areas of China. This paper aimed to examine the effects of the combined application of straw mulch and buried straw layer on soil moisture, soil salinity and growth of sunflower (Helianthus annuus L.) plants. A three-year field experiment was conducted in the Hetao Irrigation District, Inner Mongolia, China. Three field management practices were studied: deep tillage with no mulch (CK), deep tillage with straw mulch (SM) and combined application of straw mulch and burying of a maize straw layer (12tha−1) at a depth of 40cm (SM+SL). Except in the second half of the first growing season, soil moisture at the 0–40cm depth was higher with SM+SL and SM than CK. Also the topsoil (0–20cm) moisture during the early growth period under SM+SL was higher than that under SM by 1.6–9.9% in 2011 and 1.6–3.4% in 2013, but the value for SM+SL was 2.1–10.4% higher than that for SM during the whole growth period of 2012. Compared with SM, the topsoil salinity under SM+SL decreased by 5.4–23.0% in 2011, 0.7–19.8% in 2012 and 4.5–31.6% in 2013 but these two mulch treatments moderately increased the soil salinity in the subsoil (20–40cm) layer compared with CK. Furthermore, SM+SL promoted sunflower growth, as indicated by taller plants and greater leaf area index. The highest sunflower shoot biomass was always obtained from the SM+SL treatment. Averaged across the three years, SM+SL increased the shoot biomass by 4.8% compared to SM and 20.8% compared to CK. The SM+SL may be an effective saline soil management practice in the Hetao Irrigation District and other similar ecological areas.