Cattle Manure Application and Combined Straw Mulching Enhance Maize (Zea mays L.) Growth and Water Use for Rain-Fed Cropping System of Coastal Saline Soils

Appropriate agronomic management is vital for the soil fertility and crop output of coastal salt-affected farmlands. Cattle manure incorporation and straw mulching are targeted as effective methods that can improve soil structure and stimulate crop growth, respectively. However, the combined application of manure and straw into salt-affected soils is less documented, especially with limited water supplement. In this study, a 3-year field experiment (2016–2018) was conducted in Binhai district, Tianjin, China to evaluate the effects of traditional tillage without manure and straw mulching application (TT), cattle manure incorporation (CM), straw mulching (SM), and CM combined with SM (CM + SM) on soil physiochemical properties, maize (Zea mays L.) growth, and water use efficiency. TT represented traditional cultivation in the study area without manure and straw application, as a control. All four treatments were carried out in a randomized block design with three replicates. The results demonstrate that CM treatment relieved salinity, decrease bulk density, and thereby stimulated root development. SM also has the advantage of improving salinity via 3-year implementation. Throughout the 3-year cultivation, CM + SM crop yields increased by >14.3% and grain water use index (GWUI) improved by >14.7% in comparison to TT treatment due to the improvement in soil properties. These benefits in soil properties, crop yield, and water use are important for minimizing salt constraints and realizing regional agro-ecological values.