View water supply in a new way to guide your systems approach to crop production
You can have the healthiest soil on the planet, perfectly balanced fertility, timely planting and still produce nothing if one crucial element is missing. You guessed it—water. But, you’re thinking, water is beyond my control.
"Not so," responds Farm Journal Field Agronomist Ken Ferrie. "Rainfall is beyond your control, but you can influence the water that’s already present in the soil or available for irrigation. Water management makes the difference between maximum yield and crop failure—with environmental stewardship as a bonus."
In this new series, we’ll detail the ways you can manage water so it’s effective—in the words of an old coffee commercial—down to the very last drop. Let’s start with several basic principles and terms that will help you think about water as a manageable input for crop production.
Water, Ferrie says, is the fluid that makes life possible—including human life because the body is 60% water. In crop production, water makes life not just possible but good.
There are 1,400 million cubic kilometers of water on the planet—if it were spread evenly over the surface, it would be 9,850' deep. So you might think moisture could take care of itself. But of course it’s not that simple.
"More than 97% of that water is in the oceans, where it is salty and not available to crops," Ferrie says. "About 2% is tied up in glacial ice caps. A little less than 1% is in groundwater more than 2,500' deep, where it is pretty much inaccessible.
As a limited yet vital input, water demands a high level of diligence. The Water Management series details how farmers can manage earth’s most valuable resource to boost yields and profit.
"Ultimately, only about 0.05% of the water on earth is available for drinking, washing and growing crops. It’s a limited resource that we need to use wisely," Ferrie says.
Water in the plant. From a technical aspect, Ferrie explains, water provides turgor pressure, which strengthens plant cells, so the plants can stand up and grow. But its most important function might be as a raw ingredient in photosynthesis.
"Water enables plants to use energy from sunlight to turn carbon dioxide into sugar," Ferrie says. "Without this process, life could not exist. The key element that water provides to the photosynthetic process is hydrogen."
Even though photosynthesis is critically important, it requires only 1% of the water in a plant, Ferrie notes. The other 99% is used to maintain turgor pressure, transport nutrients and sugars and cool the plant.
"One place you can manage water is in the plant," Ferrie says. "Management techniques include variety selection, row spacing, population, fertility and variable-rate planting."
Water in the soil. The second place you can manage water is in the soil. There, water provides nutrients to the plants by making root interception, mass flow and diffusion possible.