Comparative study of straw mulching and interplanting patterns on water use efficiency and productivity of the maize-soybean cropping system

This study aimed to assess the influence of intercropping and straw mulching on dynamics of soil water and thermal condition, with a specific emphasis on the content of inorganic nitrogen (N)—including NH₄⁺–N and NO₃–N—and, ultimately, their effects on crop yield and water-use efficiency. The experimental design employed in this study featured a split-plot arrangement of treatments, where the main plot comprised soybean (Glycine max L. Merill) monoculture (S), maize (Zea mays L.) monoculture (M), and soybean/maize intercrop (I), while subplot was comprised of various levels of straw mulch including no mulch application (M0), 4.8 t ha⁻¹ (M1), 7.2 t ha⁻¹ (M2), and 9.6 t ha⁻¹ (M3). Results showed that straw mulching and planting patterns significantly affected the dry matter and grain yield of maize and soybean. Intercropping promotes maize dry matter and yield but inhibits soybeans. Soil moisture fluctuations in the 0–30 cm soil layer are influenced by rainfall dynamics, while the 40–60 cm soil layer remains relatively stable. Increasing straw mulch positively correlates with soil moisture, with intercropping displaying significantly higher moisture levels than monoculture. Soil temperature fluctuations decrease depth, with the 0–15 cm layer exhibiting greater variability. Straw mulching correlates with decreased soil temperature, and intercropping significantly lowers soil temperature than monoculture. Crop water productivity increases significantly with straw mulching and intercropping. The intercropping with 9.6 t ha⁻¹ straw mulch (M3I) had the highest water productivity and water use efficiency (WUE) for maize, while soybean monoculture with 9.6 t ha⁻¹ straw mulch M3S) had higher WUE for soybean. In conclusion; straw mulching and intercropping improve crop yield, soil moisture, water productivity, WUE and soil temperature regulation. These findings underscore the potential of these sustainable agricultural practices, offering valuable insights for guiding water-conserving and high-yield agricultural production.