Fertilizer placement for cereal root access

Conservation tillage, which involves surface crop residue ( 16 ), often results in seedbed and near-surface soil environments that are not always as suitable as they might be for growth of cereal grain seedlings ( 25 ). Microbial decomposition of surface residue or partially incorporated residue immobilizes mineral nutrients, particularly nitrogen. Competition for these nutrients in early spring limits the supply available for uptake by plant roots ( 1, 3 ). Without incorporation of fertilizer, rain or irrigation is required to move mobile nutrients down into the root zone. Immobile nutrients are not accessible unless they are physically placed where roots can grow to them. Spring crops grow most rapidly when they have access to nutrients immediately following emergence. Delayed access may limit early seedling growth and reduce grain yields. Placing fertilizer deep in the soil usually offsets the immobilization effects some, but proper location is important for maximum root access by young plants. Small amounts of starter fertilizer can be banded with the seed. Applying the entire crop requirement. However, may delay or stop seed development ( 2, 6, 12, 15, 17 ). Fertilizers can be banded deep in the soil either prior to planting or in the interrow zone at planting time. But either method …