Ridge and furrow cultivation raises water and nitrogen use efficiency and crop climate adaptability

Ridge and furrow (RF) crop cultivation systems with crops planted in furrows or on ridges, modifies soil properties by altering field topography and optimizing water and N fluxes as well as temperature regime. The RF cultivation can be used to mitigate environmental stresses that restrict crop production, such as drought, low temperatures, high soil bulk density, and even flooding. There is broad diversity of RF systems, each of which is tailored to specific objectives under local climatic and soil conditions. Despite the worldwide spread and importance of these cultivation systems, there is no clear systematization of RF fields or evaluation of changes in water and N fluxes compared with flat cultivation. Here, we performed a meta-analysis and literature review to provide a comprehensive characterization of RF cultivation on the basis of the main aims, and management of water and nutrients. The most important difference between RF and flat cultivation practices is the complete change in water infiltration and fluxes in soils as well as associated nutrient losses, especially nitrogen (N). Furrow planting involves the collection of rainwater in the rooted zone, providing an advantage under droughts. Increasing the N content in rooted soil is the main advantage of ridge planting, but the low soil moisture in ridges may limit N availability. Covering ridges with mulch optimizes water redistribution and reduces N leaching, NH3 volatilization and N2O emissions, which in turn increases the benefits of RF cultivation. With a broad range of crops, RF cultivation raises yield and N uptake, and generally increase N use efficiency (NUE; yield / N uptake) and water use efficiency (WUE; yield/evapotranspiration (ET)), and reduce ET, compared with flat planting. RF cultivation has good adaptability to climate change, effectively addressing various environmental stresses. Moderate temperatures maximize the rate of yield increase under RF cultivation. Furrow planting can more effectively increases yields in dry climates than in wet climates. Under humid conditions, ridge planting retains moisture in the ridges, thereby increasing WUE, NUE and yield, while reducing waterlogging. Factors such as microtopography, mulch coverage, stemflow, irrigation, climate, and plant uptake influence water and N redistribution, vertical and lateral infiltration. Lateral infiltration is critical in regulating soil moisture and water storage in the root zone, thereby reducing water loss and raising water uptake by roots. Preventing fertilizer N loss through water infiltration and maintaining N availability increase NUE and WUE, while reducing N losses. Modelling and upscaling of water and N fluxes in RF systems are highly challenging. Future research should focus on the redistribution of factors limiting crop growth via RF topography and mulching as well as to consider the specifics of soil surface modification.