With a depressed farm economy, an increase in the cost of nitrogen fertilizer was the last thing that producers needed. Once again tight economics are forcing tough decisions. But before you decide to take drastic fertilizer measures, you should know what the cost of a hasty decision could mean to your bottom line.
This winter as I visit dealers and producers, I have been amazed at the number of producers considering zero fertilizer inputs for 2001. What concerns me is this decision is based merely on the rise in the cost of nitrogen fertilizer. Yes, the price of N is up. Some predictions made in late February put the cost of N this spring at 42 cents to 49 cents per pound. Those prices are scary. But let's consider a few options.
First of all, a soil test will go a long way toward uncovering the base level of nutrients in any given field. I know, I know - this is when most producers tune out and decide they know what is best for their fields. But without some base line data (and a soil test is the best way to get this information), it is impossible to know where your field lies on the response curve (figure 1).
By knowing a field's position on this curve you can estimate its response to a given combination of inputs. For every dollar invested, you want at least an equal dollar returned. But generally, "a return of $1.50 for the last dollar invested allows for the risk of less than optimum conditions in the use of fertilizer." (Fertilizer Economics, Sask Ag and Food).
The lower the level of residual nutrients in the soil, the greater the crop's response to an increase in a deficient nutrient. In order to meet 100% yield potential, all essential nutrients must be available in optimum quantities. As shown in the classic response curve (figure 1), the bottom axis represents increasing levels of required nutrients. If any single input (for example nutrients, water, heat) is less than optimum, the curve will peak at a yield level far below 100%.
So what does this mean? If you have high levels of residual soil nutrients, in particular N, you may not require as much fertilizer N to attain a target yield. The key is to know what those residual soil levels are so you can determine what inputs are required to attain yield targets.
When you know the level of fertilizer required, you can determine the cost (the bad news). At this point you can reset your target yields lower (if the news is really bad). By doing these calculations you can modify your input dollars and know what yield to realistically expect from those given inputs.
So as you grapple with these tough decisions, it may be beneficial to do your homework first (get a soil test) and see how far those stretched fertilizer dollars can take you in 2001. Good Farming.