Don’t forget: The weather experienced during a crop year has the greatest effect on crop yields. Crops need sunlight, warmth, moisture and nutrients to grow. When crops are grown under rain-fed conditions, the only need we can supplement is nutrients by adding fertilizers and livestock manures as appropriate. Access to irrigation allows addition of water if moisture is in short supply, but we can’t do much if rainfall is excessive. The reality is that farmers are at the mercy of the weather.
Most of the time the weather is conducive to reasonably good crop production, but sometimes we receive insufficient moisture and/or warmth, and crop yields are poor. In contrast, there are those extraordinary crop years when all the crop needs are supplied in just the right combination. The question can be asked, Do farmers fertilize sufficiently for that above-average crop?
We could always perfectly apply fertilizer inputs if we knew what the weather was going to do during the crop year. The challenge is that we don’t know what the exact weather will be until after it happens. At the end of the crop year we can look back and see where adjustments could have been made to the fertilizer program. If we had cool and droughty conditions, lower fertilizer rates would have been adequate for the reduced crop potential. Also, in an ideally warm and sufficiently moist year, in many cases above-average crop yields could have been even higher if higher fertilizer rates were used.
In practical terms, most growers apply nutrients in anticipation of a slightly better-than-average crop year. But there are some nutrient management strategies that could be beneficial in those much better than average years. One is regular soil testing for plant nutrients that can be gradually built up and maintained at optimum levels. Another strategy is always being capable and ready to supply additional nitrogen fertilizer as an in-crop application if much better than normal crop growth is experienced. This would allow growers to supply ample nutrients to optimize crop yields when they experience better than average weather.