Understanding Crop Management – A Key to Higher Yields

DR. DENNIS B. EGLI 

PRINCETON, KENTUCKY

What do we mean when we use the term ‘crop management’? Usually it refers to the techniques, processes and practices used to produce our crops. We seldom think deeply about this general term  – we are too engrossed in the details of growing the crop to think about the overall process. I think we will all benefit if we spend a little time thinking about exactly what ‘crop management’ means.

Crop management has two basic objectives: to increase yield or to improve efficiency (produce the same yield with fewer inputs or higher yield with the same inputs). In recent years, a third objective has gained importance – the need to reduce the impact of crop production practices on the environment.

To increase yield, crop management practices are designed to improve the crop’s environment (environment includes both the above- and below-ground components of the system) by supplying missing raw materials for crop growth or by removing negative aspects from the crop’s environment. We fertilize to supply nutrients, we control weeds to reduce unwanted competition, we irrigate to minimize moisture stress, and we control insect or disease outbreaks. Population and row spacing are adjusted to maximize solar radiation interception. Varieties that are resistant to disease or insects essentially remove negative factors from the crop’s environment.

Temperature and solar radiation levels affect yield, but we cannot manipulate them directly. Water also falls into this category when irrigation is not available. We can, however, manipulate planting date and variety maturity to put critical crop growth stages in a more favorable  environment. Larger changes require moving production to a more favorable location. 

The goal of these practices is to improve the environment the crop is growing in and move it closer to the ‘perfect’ environment that will maximize yield. The perfect environment sets a limit on yield gains that can be expected from management, in fact, the yield increment from additional management will be smaller as the crop’s environment gets closer to the perfect environment and may not produce an economic return. 

Management practices that improve yield eventually reach a saturating limit where no more yield improvement is possible. Adding fertilizer only increases yield until the needs of the crop are met. Adjusting row spacing provides no benefit once complete ground cover is achieved. This so-called saturation effect also limits the effect of management on yield.

 Maximizing yield requires getting as close to the perfect environment as possible, but that may not maximize the bottom line. It seems that producers sometimes forget this important distinction as they chase higher and higher yields.       

Approaching the perfect environment does not mean that no more changes in management will be needed. The environment we grow our crops in may change over time. The appearance of new diseases or insect pests, changes in temperature or moisture availability, perhaps driven by climate change, will create new opportunities for management to push the environment back towards perfection.

Genetic improvement of our crops provided the basis for the large historical increases in yield. Some aspects of variety selection (e.g., disease and insect resistance) fit into the ‘perfect’ environment scenario, but others (e.g., improvement in the plant’s fundamental capacity to produce yield) doesn’t. This exception does not negate the value of the ‘perfect environment’ concept. 

A second objective of crop management is to improve the efficiency of production (the same yield with fewer inputs, for example). Efficiency is important because it directly effects the producer’s bottom line, even though it does not necessarily increase yield. After all, a cropping system can survive only if the producer makes a profit (in the marketplace or from government subsidies).

 Improvements in efficiency are often the result of new technologies that make new production practices possible. Current examples include variable rate equipment that may reduce inputs, and the new see-and-spray sprayers that claim reduced herbicide inputs while maintaining weed control. These and other technological advances may lead to increased efficiencies by reducing inputs while maintaining yield. 

The limitation to constantly improving efficiency is the availability of new technology or finding new ways to use old technology. Selling efficiency is not as glamorous as selling high yields (how many efficiency contests are there?), but the rewards to the producer can be substantial.

And then there are management practices that don’t increase yield or efficiency; they simply reduce the negative effects of agricultural production systems on the environment. Management practices in this category are important today and they may become more important as societal concerns about the environment increase. Unfortunately, they are not always popular because the yield or efficiency payoff often comes in the distant future, if at all. 

 Identifying our goals when researching or modifying our crop management systems will make us better (and richer) managers. Are we chasing higher yields or improved efficiency? Evaluating a production practice for improvements in efficiency requires a different research approach and data collection than simply evaluating its effect on yield. If yield is the only focus, useful practices may be abandoned because they did not significantly increase yield, even though they may have improved efficiency and the producer’s bottom line or reduced environmental damage.

In reality, crop management practices don’t always fit neatly into these three categories. Crop management, unfortunately, is not that simple. The fact that a single management practice fits into two or three categories (e.g., increases yield and increases efficiency) does not negate the value of using the three separate categories when we think about crop management.  

The primary message of this article is that we will do a better job of managing our crops and researching management practices if we think a little bit more about the three categories of crop management when determining our objectives – are we trying to increase yield (which will get more difficult as we approach that perfect environment),  to improve efficiency (may depend on new technology), or save the environment? Our love affair with silver bullets and higher yields often overshadows any considerations of efficiency or saving the environment; perhaps a little more balance may lead to more profitable and sustainable crop management systems.  ∆

DR. DENNIS B. EGLI: Professor Emeritus Plant and Soil Sciences Department, University of Kentucky