by KEITH REID

This makes it tempting to cut fertilizer costs, but cutting indiscriminately will mean fewer dollars in your pocket at the end of the season. The key to maintaining profitability this year will be skillfully choosing what to keep, and what to drop, from your fertilizer program.

You won't be able to manage your nutrients if you don't know what you have in the soil to start with. This means that soil testing should be one of the last expenses you cut. There may, however, be some room for savings. If you have been on a regular sampling program, and have developed a history for all fields that is no more than three years old, then delaying sampling for a year is unlikely to introduce significant error. The danger is that you will slide into longer intervals between sampling.

The biggest benefit to soil sampling is characterizing the average value for the field. The additional value to smaller sampling units is not as large, so you can save some money by using 25-acre field units rather than detailed or grid sampling.

Lime. If your soil is too acid for the crop to grow, then the rest of the money you spend on fertilizer will be wasted. If there are savings to be realized, it is from liming only to the needs of the crop you are growing (corn is more tolerant of acid soils than cereals or soybeans, and they are both more tolerant than alfalfa). Since trucking is such a large part of lime cost, using the closest good quality source will save money.

Nitrogen. The easiest decisions are around nitrogen fertilizers on legume crops like soybeans or alfalfa. Responses to added N have been inconsistent, and when they did occur, they were small. Save the nitrogen for crops that will respond to it.

Anything you can do to maximize the availability of nitrogen from organic sources will reduce the amount of fertilizer you need to apply. Account for the nitrogen in manure or previous legume crops. Apply manure evenly and incorporate it quickly to retain as much of the available N as possible. It is even worth weighing a few loads of manure and measuring the area they cover, so you know how much manure you are actually applying.

For corn, the nitrogen fertilizer recommendations are based on a nitrogen:corn price ratio of five (that is, it takes five pounds of corn to pay for one pound of N). As the price ratio widens to eight, the optimum rate of nitrogen drops by about 12 pounds per acre. With the current corn and nitrogen prices, the ratio is approaching 10, but we hope there will be opportunities to price corn at higher values before spring.

This means that you can justify reducing N applications by 10-15 pounds per acre if you have been applying N at the maximum economic rate (MERN) already. If you should happen to have been applying insurance rates of N above the MERN, then you can reduce rates even more without hurting your bottom line. The caution is to avoid cutting rates too much, where the value of the yield loss is greater than the cost of the fertilizer.

The same pattern of reduced N recommendations with higher N prices will hold for other crops, although the relationship has not been as well established.

Phosphorus. The biggest bang for your dollar is going to be from banded phosphorus, particularly on corn or cereal crops. Broadcast applications of phosphorus for soil test build up or maintenance will provide much smaller responses. If the soil test values are very high, you can probably forego any P application without causing yield loss.

Potassium. Knowing your soil test value is the key to managing potassium fertilizer. Many clay or clay loam soils have huge reserves of potassium, so it makes sense to use some of this investment, rather than continually depositing into the bank. On the other hand, sandy soils can quickly become depleted in K, and yield losses can be severe.

Manure, particularly from cattle, is an excellent source of potassium, so target manure applications on those fields with the highest potash requirements.

Micro and secondary nutrients. There are two situations where these nutrients are used -- correcting a well-documented deficiency and as insurance for a deficiency that might occur. In the first instance, the cost is an investment in higher crop yields or quality, and should be kept in your fertilizer program. The second situation is more akin to buying lottery tickets, except that there isn't a big jackpot for the rare times that it pays off. Unless these nutrients can be included in the fertilizer program without extra cost, they are better left out.

The final point is to make sure that the rest of your crop production program is in order -- crop rotation, hybrid selection, timely tillage and planting, weed control, and so on. Only then will you get the maximum return to your fertilizer program. BF