AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335
Summer 1999, No. 6
All nutrient management plans should be based on soil tests. Too often though, they start and end with collecting a composite soil sample from each field on the farm and following the soil test recommendation. Soil test results and recommendations are excellent tools, but should only be a starting place in nutrient management planing. Soil test results can be made more powerful when combined with the following information.
On farms where animal waste is a resource, experiences with nutrient management plans indicate that nutrient imbalances are not uncommon. The nitrogen, phosphorus, potassium ratio of animal wastes, and the disproportionate crop uptake and removal of these three nutrients often result in elevated phosphorus levels in some fields. Many of these same fields may benefit from potassium addition. With nutrient management plans, these fields, or sub-fields, can be better identified for management changes. Animal waste applications may be adjusted or redirected to other fields to better match plant nutrient requirements. Nitrogen and potassium rates can be planned to bring soil fertility levels in balance with plant demands.
Most soil testing labs offer recommendations that are based on the probability of response to lime or nutrient additions. Many also consider the requirements for building soil tests to research-supported optimum levels over a reasonable period of time. These different soil test recommendations are often labeled as "lab recommendation philosophies." In reality, every farmer should consider not just what might be beneficial this year, but also for the long term. This means that soil test "sufficiency", "build-and-maintenance", and "drawdown" approaches may be equally viable. Each of these approaches should be considered on every field on every farm and probably on sub-field units as well.
Nutrient management plans can be tailored to individual producer needs. With nutrient management plans, farmers can develop short-term and long-term strategies for each field to achieve: soil fertility goals, high yields, field-by-field environmental objectives, and maximized profit potential. Nutrient management plans...? The prime time may be 1999!