Management Zone Delineation Based On Soil Properties Measured During The Reproductive Stage Of Rice In The Field

Identification of key soil properties is an essential prerequisite to delineating the management zone (MZ), which is traditionally done by selecting soil parameters before crop planting. However, soil properties during sensitive stages of crop growth may have a greater effect on the MZ delineation than those before planting. This study is aimed to determine whether inclusion of soil properties measured in surface layers during the reproductive stage of rice could enhance the appropriateness of MZ delineation based on sodic/saline-sodic paddy fields. When including soil variables during the reproductive stage, with/without soil variables before planting, a similar MZ pattern (MZ pattern 3) was generated. Furthermore, when including soil variables during the reproductive stage and rice yield components, with/without soil variables before planting, another similar MZ pattern (MZ Pattern 4) was generated. Compared with other patterns, the MZ pattern 4 showed higher relative variances for rice yield and the mean of its most important yield-influencing factors, with lower coefficient of variation (CV) in all MZs compared with the whole-paddock CV. Likewise, this pattern showed improvement in discriminating soil and rice variables among MZs. These findings confirm that inclusion of soil properties during the reproductive stage of rice has potential for enhancing the appropriateness of MZ delineation. This study also necessitates inclusion of carbonate-derived variables when delineating MZs in sodic/saline-sodic paddy fields. Our results encourage further investigation of the role of soil properties in surface soil layers at critical crop growth stages in MZ delineation under multiple soil and climatic conditions.