Many Island potato producers are now practising conservation tillage prior to planting potatoes. Conservation tillage or residue management as it is often referred to can be practiced on any field going into potato production where the previous crop was a forage or cereal. The objective of residue management is to leave the maximum amount of plant residue from the previous crop, on the soil surface after each stage of cultivation.
Residue management depends on the previous crop planted in the rotation. Cereal crops should be harvested with a combine equipped with a straw chopper and spreader. In order to maximize residue levels, the straw must be left on the field. The straw must be chopped and uniformly spread so that is does not pose problems during potato planting and harvesting. A tillage pass with either a tandem disc or a chisel plow equipped with a leveller, as soon as possible after harvest, will allow unharvested grain to get good soil contact, germinate and produce an excellent cover crop before winter. Spring tillage with an implement capable of cutting residue, tilling the soil to an acceptable depth and producing a level seed bed is required.
Residue managed potato production techniques on land where the previous crop was an under-seeded cereal will depend on the underseeding mix used. During the combine operation, the cereal crop should be cut less than fifteen cm above the ground level and the straw should be chopped and uniformly spread over the field. If the field contains grasses, it requires a fall application of glyphosate in order to perform residue management. If the forage stand contained only perennial legumes such as red clover, crimson clover or alfalfa, the field should be tilled in mid to late October. Spring tillage requirements, prior to planting potatoes, would be similar to those used with non under-seeded cereals. The perennial legume will be actively growing when spring tillage is performed but can easily be controlled with herbicides after the potatoes have been planted.
Residue management results in reduced tillage costs because there are generally fewer equipment passes in a conservation tillage system. Producers typically save eigthy-five dollars to one hundred and twenty five dollars a hectare (thirty-five to fifty dollars an acre) with residue management. Surface runoff volume and speed is reduced, water infiltration is improved and soil structure is stabilized resulting in lower erosion rates. Studies have shown erosion losses to be eighteen times lower after potato planting under conservation tillage, when compared to conventional tillage systems.
In addition, soil moisture levels are improved and research has shown that potato yields increased ten percent on residue managed plots as compared to conventional treatments in a three year study.