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Effects on Soil Erosion
Crop rotation can greatly affect the amount of soil lost from erosion by water. In areas that are highly susceptible to erosion, farm management practices such as zero and reduced tillage can be supplemented with specific crop rotation methods to reduce raindrop impact, sediment detachment, sediment transport, surface runoff, and soil loss.

Protection against soil loss is maximized with rotation methods that leave the greatest mass of crop stubble (plant residue left after harvest) on top of the soil. Stubble cover in contact with the soil minimizes erosion from water by reducing overland flow velocity, stream power, and thus the ability of the water to detach and transport sediment. Among most large-scale production crops, wheat consistently leaves a significant mass of stubble after harvest. Wheat production supplemented with no till or reduced till management systems can typically yield 90% post-harvest soil cover with up to 15 months of stubble retention. The amount of stubble mass retained over time governs whether a crop will be successful in controlling erosion. Crops with little stubble mass retained over time should not be planted following a plant production system with similar characteristics. Sunflowers for example typically produce less than 40% soil cover after harvest with very little stubble remaining after cultivation. This leaves a significant percentage of the soil susceptible to erosion. However, when sunflower crops are rotated with wheat crops in production, the soils are less prone to erosion because the high-stubble producing wheat crops are followed by the low-stubble producing sunflower crop. A corn – soybean crop rotation in a no till system works similarly. Corn plants leave substantial residue mass after harvest. Soybeans, a relatively low-residue producing plant, following corn will have sufficient cover from the previous crops corn residue to limit soil losses. It is important to avoid mono-cropping low-stubble producing plants when attempting to reduce soil loss.

The additional crop residue added by rotation with crops with substantial biomass will also enhance soil structure. Stubble cover will prevent the disruption and detachment of soil aggregates that cause macrospores to block, infiltration to decline, and runoff to increase. This significantly improves the resilience of soils when subjected to periods of erosion and stress.

The effect of crop rotation on erosion control varies by climate. In regions under relatively consistent climate conditions, where annual rainfall and temperature levels are assumed, rigid crop rotations can produce sufficient plant growth and soil cover. In regions where climate conditions are less predictable, and unexpected periods of rain and drought may occur, a more flexible approach for soil cover by crop rotation is necessary. An opportunity cropping system promotes adequate soil cover under these erratic climate conditions. In an opportunity cropping system, crops are grown when soil water is adequate and there is a reliable sowing window. This form of cropping system is likely to produce better soil cover than a rigid crop rotation because crops are only sewn optimal conditions, whereas rigid systems are sown in the best conditions available. Crop rotations also affect the timing and length of when a field is subject to fallow. This is very important because depending on a particular regions climate, a field could be the most vulnerable to erosion when it is under fallow. Efficient fallow management is an essential part of reducing erosion in a crop rotation system. Zero tillage is a fundamental management practice that promotes crop stubble retention under longer unplanned fallows when crops cannot be planted. Such management practices that succeed in retaining suitable soil cover in areas under fallow will ultimately reduce soil loss.