As more and more Island fields are turned over to potato production, the need for soil conservation measures becomes increasingly necessary. Fields at low, medium, or high risk of erosion will require different combinations of measures to reduce soil loss. Fields at low risk for erosion can be protected using annual crop rotation, a long-term strategy involving the planting of cereals and forage crops in sequence with potatoes. Crop rotation improves soil organic matter levels, increases rooting depth, reduces soil compaction, and improves soil fertility and weed control. Together, these improvements result in better crop quality and higher yields.

In combination with crop rotation, fields at moderate risk for erosion require conservation tillage, winter cover, strip cropping, and cross slope farming. Conservation tilling (or residue management) protects the soil from the impact of rain by creating the effect of small dams and windbreaks. This technique involves leaving plant remnants from the previous season’s crop on the field when planting for the current season. The planting of winter cover crops, such as fall rye and winter wheat, is the most cost-effective approach to soil conservation. Fields planted with early-maturing potato varieties are best suited to winter cover, giving the cover crop sufficient time to establish itself before the onset of winter. In addition to reducing erosion, cover crops add organic matter, improve soil structure, suppress weed growth and, in the case of legumes, provide valuable nitrogen for the next potato crop. Where later potato varieties are grown, straw or hay mulches can provide a good alternative winter field cover.

Cross-slope farming reduces the erosive effects of the channels normally created during ploughing and cultivation. Tilling and planting across the slope creates a series of dams that slow runoff and redirect it, allowing it to soak into the ground or to float between the rows of potatoes until it reaches grassed headlands or waterways. On longer slopes, cross-slope farming is best combined with strip cropping and/or terraces. In addition to reducing the risk of erosion, cross-slope farming increases the availability of moisture during the growing season. Moreover, cross-slope farming entails no additional expense to farmers.

Strip cropping combines the soil and moisture conservation of cross-slope farming with the soil-building advantages of crop rotation. This measure sees farmers alternating strips of grain and/or forage crops across a slope. Grass headlands further protect against erosion and provide access lanes to each strip. Three-year strip rotations of potatoes, grain, and hay reduce erosion by 75 percent compared to farming one crop planted in rows up and down the slope.

Areas at high risk for erosion should combine the foregoing elements with erosion control structures such as terraces, surface inlets, grassed waterways (all of which slow or redirect water flow) and hedgerows (designed to protect against wind erosion). The planning, design, and construction of such structures are best handled by qualified professionals. Terraces break up long slopes into a series of shorter slopes, with each successive terrace catching surface water from the one above it. Surface inlets or grassed waterways carry the intercepted water to prevent it from travelling the length of the slope. These broad, shallow grass-covered channels control gully erosion (where water collects and flows through natural depressions). Unfortunately, waterways permanently remove land from cereal and row crop production. Surface inlets and underground piping systems avoid this drawback by intercepting runoff, piping it, and discharging the water in a safe and convenient location.

Hedgerows are treed windbreaks that provide many benefits to potato production. Erosion control is effected by reducing wind speed at ground level and by trapping snow on the field, thus keeping it covered during the winter months. Well-established hedgerows, planted at right angles to the prevailing winter winds, can control snow drifting for a distance equal to ten times the height of the break. Wind speeds over down wind areas can be reduced for twice this distance.

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