Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Fluid Journal 1993-1995
2 Fluid Journal Fall 1994 concentration of most of the nutrients up in that zone where they might have been incorporated. Then the question is, will plant roots be obtaining those nutrients up in the top part or below? One plus with reduced tillage is you do have conditions favorable for good root growth in the upper layer of soil. FJ: What micronutrients should be added to starters? Zinc and manganese especially. Those are the main two. Now with boron, the rate must be fairly low, because you can't have too high a rate of boron in the row too close to the seed. FJ: What about iron? Similar to zinc. One problem with iron is that soil application of many iron sources is not effective. Iron oxidizes quickly in the soil and becomes unavailable. So it's not a good practice. The keys to iron are knowing where the potential deficiency is, and trying to grow crops that are tolerant to lower levels of iron in the soil. There are studies on various varieties of corn and how they differ in tolerance to low levels of iron. Same is true for soybeans and sorghum. FJ: We're seeing problems like this with corn in the Central Platte Valley. They can't rotate, like with sorghum and soybeans, so getting another crop in is not a very good option. They're all pretty sensitive to iron deficiency. What would you suggest they grow? They should check with their seed dealers to see if they have some corn varieties that are more tolerant. They are identifying these varieties and I think some might work in that region. It's the easiest way I know of to control iron deficiency. FJ: Are there any other iron additives that work in the soil? What about chelates? There is one chelate, but it's really expensive. It needs to be used mainly for high value crops. So it isn't really economical. Iron sulfate is most economical to buy, but it doesn't stay available in the soil too long. FJ: That's where you got involved with "gelled" fertilizers, too? That's right. We will see potential, but they aren't ready to market yet. FJ: What are the most common micronutrient deficiencies in the Corn Belt? Zinc is the most widespread. Manganese would be next, then boron. Following this, we have iron and copper. Mainly, I'd be concerned with zinc, manganese, and boron for crops such as corn, soybeans, alfalfa, sugar beets and vegetables. FJ: Foliar applying micronutrients on cotton seems to be a common practice. How does foliar fit into a sound fertility program? Foliar fertilization works well with certain micronutrients. It's a convenient way to apply them four or five times a year and get feeding all through the summer. The main ones for cotton are manganese and boron. Manganese is used on cotton in soils high in pH. Generally, it is applied with starters, although I expect some is also foliar sprayed. FJ: What forms of manganese would you foliar apply? Manganese sulfate is best. It's one hundred percent water soluble. FJ: What micronutrients can be added to fluid fertilizers? Well, zinc is widely used with fluid fertilizers, but there is a difference between zinc and manganese. Manganese reacts with polyphosphate in a 10-34-0 solution. So it doesn't work quite as well. Sometimes manganese oxide is used in suspensions because there's less reaction. There is usually no problem applying one to two percent zinc in starters. Boron is also no problem. The only precaution is there's a possible effect on seed germination with starter fertilizers banded close to the seed row. FJ: Should micronutrients be broadcast or banded? Broadcasting is common. With zinc there's quite a difference between band and broadcast in terms of effectiveness. Comparing broadcast to starter, the general rule is that you put on double the amount of zinc if it's broadcast. Some say the ratio should be even higher. With boron, it wouldn't make any difference in a one to one ratio. Copper reacts in the soil pretty much like zinc. So what we say for zinc pretty well holds true for copper. FJ: Is there much tissue testing going on with micronutrients? Not as much as there used to be. Tissue tests should be used to verify your current fertilization program. They reflect the nutrient status at the time you sample. So it's a matter of using it as a checkpoint. It's also a great way to help verify nutrient deficiencies. Some growers have a standard practice of making these tests as a check on their fertility program. FJ: Where do you see the environmental movement affecting agriculture? Mainly on use of nitrogen. There is a potential for leaching nitrates into ground water. Or, when applying
Fluid Journal 1996-1998