Source: University of Wisconsin, Agronomy Department
Farmers need to manage nutrients and pesticides carefully to both avoid adverse effects on the environment and to reduce costs of purchased inputs. But growers also must maintain a production level that will result in profitable returns. Joe Lauer, corn agronomist, University of Wisconsin, said successful farm operations involve more than balance sheets of "input vs. output." There are many relatively "cost- and environment-neutral," sometimes "invisible," management techniques that can have substantial impacts on output and return per acre.
The guidelines listed below have been gleaned from many sources. They are timeless kernels of advice because most of our advice for crop production efficiencies is the same old advice we've been handing out for years! But, the current economic climate creates "teachable moments." Use common sense. Don't make drastic changes in farming operations for next year. Remember Mother Nature holds the ace. How many farmers know what their inputs are, let alone their costs per acre or per bushel? It is hard to trim costs if you don't know your inputs. More and more, it's the dealer who best knows the details.
A sound fertility program is most important during financially distressed times. Obtain a soil analysis and develop a soil fertility program based on this analysis. Fertilizer needs vary from field to field and within fields. Fertilize each field based on need. Fertilize low fertility fields first and then fields with high fertility. Fields high in phosphorus and potassium may not require additional nutrients for a year or more. This practice will give a greater return for each fertilizer dollar than reducing fertilizer rate on all fields uniformly.
Apply only those nutrients that are determined to be limiting yield. As yet, many micronutrients are not recommended for most soils by agronomists. Something applied when not needed is an additional production cost and reduces profit.
Banding phosphorus and potassium with the planter has proven to be more efficient at low soil test levels than broadcast applications. To insure efficient uptake of phosphorus and potassium, place them beneath the soil surface. Roots, nutrients and moisture must be in the same area for nutrient uptake to occur.
Set realistic yield expectations based on previous history and the relative productivity of your field. In fields where the previous crop was a legume or another crop other than corn, reduce nitrogen rate to take advantage of nitrogen left from the previous crop. Manure commonly contains appreciable amounts of nitrogen, phosphorus and potassium. Incorporation of manure greatly reduces nitrogen loss. Adjust fertilizer requirements based on amounts of nutrients available from previous crop and/or manure application.
On soils with less than adequate drainage, consider the side dress application of most of the nitrogen. This will reduce the potential for nitrogen loss due to denitrification. To insure vigorous early growth, be sure to add some starter nitrogen. When side dressing or knifing in anhydrous ammonia close to planting, add some starter nitrogen.
Minimize surface volatilization losses of urea in reduced tillage by either surface banding or injecting to reduce contact of urea with surface litter.
To obtain optimum Nitrogen use efficiency one must Balance the logistics of N application with the need to minimize N loss potential e.g., the ease of "weed 'n feed" vs. opportunity for volatization or trash tie-up. Remember to consider denitrification and leaching potential of the soil.
Starter fertilizer issues include 1) High soil P & K levels = don't use P & K starters; 2) High soil P & K + early planting and/or no-till = Nitrogen most important; 3) High soil P & K + warm seedbed = don't use any starter; and 4) 2x2 placement versus "popup" = Higher "safe" rates w/ 2x2 and greater response
Under high soil P & K, the recommendation is replacement. Little, if any, effect on yield if no additional P & K applied for several years
Lime application can be a profit-maker, especially at pH levels less than 6.0. One of few opportunities for VR technology to return profit to farmer
With micronutrients, the profit margin to dealer is much greater than N-P-K fertilizers. The profit margin to most farmers is much more questionable. MOST cropland does not respond to application of micronutrients. Use both soil test and plant tissue analysis to develop recommendations
With root "enhancers," the profit margin to dealer is very attractive. The profit margin to most farmers is much more questionable. There is little factual evidence for crop benefit.
Recommendations when prices are down:
1. Sample soil and follow soil test recommendations. Accurate soil tests let you reduce fertilizer costs by taking advantage of nutrients supplied by the soil. If you don't soil sample, you're losing money-either by applying more fertilizer than your crop needs or not enough for it to reach its yield potential.
2. Environment and soil characteristics influence yield more than fertilizer rate. Fertilize for realistic yield goals. A reasonable yield goal is the average of the three highest yields for the past five production years for that crop in a given field.
3. Apply most of the nitrogen as a sidedress and base your rates on the pre-side dress nitrate test.
4. Reduce or eliminate phosphorus fertilizer applications. Additional phosphorus isn't required when soil test levels are above a certain level. Most farm fields in WI have adequate phosphorus levels.
5. Utilize manure nutrients whenever possible. Test manure, calibrate your spreader and apply manure based on soil test recommendations. Pre-side dress nitrate testing has also been used to measure the amount of N available to corn from fall manure applications.
6. Apply ag lime as needed. Applying lime when needed will increase nutrient availability and improve yields. Select liming materials based on their neutralizing value; mesh size and magnesium content (if magnesium is recommended). Check into local sources of byproduct liming materials.
7. Apply micronutrients only where a response is predicted and likely to occur. Highly responsive crops will show a yield response to a specific micronutrient if the soil test level for that nutrient is low. Zinc (corn), manganese (soybeans and wheat) and boron (alfalfa) are the only micronutrients that should be applied on mineral soils.
8. Take advantage of rotating crops. Soybeans contribute 30 pounds of actual N per acre to the following corn crop.
Source: University of Wisconsin, Agronomy Department