A uniform stand and herbicide activation are two goals of good water management from the start.
The abundant rains of last year and through the winter should not be expected to continue, and producers should be ever mindful of the importance of using what water is available wisely. While the critical water-use period for peanuts is from 40 to 110 days after planting, water management at planting should not be overlooked since it affects plant stand, root growth, overall seedling and plant health, weed control and, ultimately, yield, grade and economic returns.
Ready The Soil, Reduce Stress
Adequate rainfall or irrigation is needed at planting to ready the soil for planting and to facilitate germination. Unless the soil has a significant amount of clay and would form a crust that would affect the seedling emerging from the soil, irrigating before planting can help to prepare the seedbed and allows the soils to warm, which improves emergence. Good water management reduces stress on the seed and seedling and leads to a uniform stand. A quickly emerging seedling and a uniform stand is the goal for reducing pressure from diseases, especially Tomato Spotted Wilt Virus. Weed pressure is also reduced in a healthy stand that has quick canopy closure. Water management is critical to this goal.
Create A Reserve
Another goal of water management at planting is to establish a moist soil profile that serves as a moisture reserve for use later at more critical water-use periods. Without a reservoir of water deeper in the root zone, the plant will not develop as deep a root system. Stressing the plant by withholding needed water or only slightly watering in order to get a deeper root system actually creates the opposite effect, and roots tend to be more shallow. The soil profile should be filled to a depth of 36 inches.
Herbicides applied at planting, whether applied at the same time or immediately after planting but before emergence of the weed or crop, typically need some type of rainfall or irrigation to “activate” the herbicide and move it from the soil surface into the germinating weed zone. Herbicides can fail if irrigation is not used and no rainfall is received. Herbicides are most effective when the soil is neither too wet, nor too dry. Herbicides should only be incorporated when the moisture level is suitable for normal tillage operations. With good water management, growers can create an environment where herbicides work effectively.
Know Your Soil
Good water management begins with knowing the soil conditions on the farm. Know how much water the soil can hold and how fast it will be absorbed. Growers should aim for 50 percent moisture in the top three to four inches of soil. Many methods for determining soil moisture are available, and growers should strongly consider using an irrigation management tool to improve efficiency. After planting, the plant’s most critical need for water is from 40 to 110 days after planting, although this may shift slightly based on the maturity of the variety planted. During this time, peanuts require one and one-half to two inches of water a week. Water is also important for the movement of calcium into the peanut pod and kernels. Improving your water management at planting improves your chances for the rest of the season. PG Information provided by the Georgia Cooperative Extension Service.