Microclimatic Studies of Legume and Cereal Crops under Various Cardinal Row Orientations and Spacing: A Review

Abstract

Row orientation and inter-row spacing are agronomic decisions that determine how a crop canopy intercepts solar radiation, exchanges sensible and latent heat with the atmosphere, and partitions the below-canopy environment between the crop and competing weeds. This review synthesises evidence on the microclimatic consequences of cardinal row orientation (north–south, east–west, and intermediate azimuths) and row spacing in major cereal and legume crops, with attention to canopy air temperature, soil temperature, relative humidity, photosynthetically active radiation interception, and their downstream effects on growth, weed pressure, and yield. Findings across wheat, maize, rice, soybean, chickpea and groundnut indicate that east–west orientation generally increases midday radiation interception and inter-row shading at mid-latitudes, benefiting weed suppression in cereals but producing more configuration-dependent yield responses in legumes, particularly within intercropping systems. Narrower row spacing consistently reduces soil temperature amplitude and evaporative loss while increasing canopy humidity, though the yield benefit is not always monotonic, and radiation gains from narrow spacing can fail to translate into yield when soil water rather than light becomes the limiting factor. The review highlights that responses are strongly latitude-, season- and crop-architecture-dependent, and that few studies directly compare orientation and spacing factorially across both legume and cereal functional groups within the same microclimatic framework. Future research priorities, methodological limitations of the existing literature, and practical implications for row-crop management are discussed.