Nulex Liquid Zinc :: Applying to Fertilizer

Applying Zinc in Fluid Fertilizers

By George Rehm and Gary Hergert Reprinted from Agrichemical Age

The importance of Zinc (Zn) fertilizers for row crop production on some soils has been recognized for many years. Over these years, researchers have described the general situations where a response to this essential micronutrient can be expected. In addition, many trials have been conducted to measure the effectiveness of various sources of Zinc on the market. In the large majority of these trials, the Zinc sources were broadcast in either a granular or powdered form. The nature and magnitude of the response to Zinc may be dependent upon the particle size of the Zinc source. As fluid fertilizers became more popular, there was a parallel development of Zinc sources which could be applied with these fertilizers. Therefore, we initiated trials to evaluate the effectiveness of several Zinc sources applied in fluid fertilizers. We chose to use suspension materials to eliminate any possible effect of particle size on crop response to this nutrient.

Soil pH

Soil pH also affects the availability of Zinc. Therefore sites having widely different chemical properties were chosen for the study. Corn was grown under center pivot sprinkler irrigation on both acid and alareous sands. In 1974, four Zinc sources (EDTA-Zinc, Nulex Liquid Zinc, ZnO, ZnSO4) were used to supply 0, 1.5, 3.0 and 6.0 lbs. Zn/acre. These same carriers were used to supply 0, .1, 1.0, 3.0 and 6.0 lbs. Zn/acre in 1975. In 1976, the NZN product was added to the study and the 6.0 lb./are rate of Zinc was discontinued. The basic suspension was made for 10-34-0, 28-0-0, 0-0-62, and contained 2-1/2% clay. The final analysis was an 8-20-6. All Zinc sources were added to this suspension to provide the required concentration of Zinc. This suspension was applied to the side of and below the seed at a rate of 200 lbs./acre at planting. Positioning of the fluid fertilizer in this way provided for an ideal relationship between the fertilizer placement and the root system of the corn crop.

Doubled Yield

Corn yields were improved by application of fertilizer Zinc at the site having an acid pH (Table 1) as well as the sites having a calcareous pH (Table 2). With placement below and to the side of the seed, small amounts of fertilizer Zinc were needed to produce maximum yield in 1974. The positioning of 1.0 lb. Zinc per are in this manner produced maximum yields in both 1975 and 1976. It's important to point out that the use of .1 lb. Zinc per are doubled yields in 1976. When this nutrient is deficient in soils, only small amounts of Zinc are needed if it is placed close to the seed at planting.

TABLE 3. Effect of rate of applied Zinc on yield of corn grown on an irrigated sandy soil having an acid pH.
Zinc Applied Pounds per Acre	Yield Bushels #2 corn per Acre
0	152
1.5	170
3.0	165
6.0	168

TABLE 2. Effect of rate of applied Zinc on yield of corn on irrigated sandy soils having pH greater than 7.0.
	Yield–Bushels #2 corn per Acre
Zinc Applied Pounds per Acre	1975	1976	Average
0	101	62	82
0.1	107	130	119
0.3	119	135	127
1.0	130	139	135
3.0	122	142	132

Various stages of Zinc deficiency were observed in 1976. The leaf showing the most severe deficiency symptom is on the far left. Deficiency symptoms gradually disappear toward the right side of the photo.

Broadcast Application

Zinc deficiencies can also be corrected by the broadcast application of various Zinc materials. In studies where dry materials were used, higher rates of Zinc were needed when Zinc fertilizers were broadcast and incorporated in the plow layer rather than applied below the seed at planting. Although broadcast applications of fluid Zinc fertilizer were not evaluated in our studies, there is no reason to suspect that higher rates of Zinc will not be needed when fluid materials are broadcast and incorporated with the soil. What soure of Zinc should be used? Is one source of Zinc more effective than another? These are questions the grower and the dealer are asking. Several sources of Zinc were compared in this study. In all cases, there was no statistical difference among the sources evaluated when yields from all rates of applied Zinc were considered (Table 3). There was some variation in the yields. This variation, however, was due to natural variation of yields in the field rather than the source of Zinc applied. The data colleted in this study show that all sources of Zinc are equally effective for corn production when applied in a fluid fertilizer below and to the side of the seed.

TABLE 3. Effect of source of Zinc on yield of corn grown on irrigated sandy soils.
	Yield–Bushels #2 corn per Acre
Zinc Source	1974	1975	1976	Average
EDTA	164	119	143	142
Nulex	165	125	133	141
ZnO	161	121	132	139
ZnSO4	164	114	137	138
NZN	—	—	136	—

Fluid sources of Zinc can add flexibility to a fertilizer program. In addition to either broadcast or application in starter fertilizer, fluid sources of Zinc can be applied with irrigation water which has a low salt content. The choice of a product for this situation should be based on its properties. It's important to emphasize, however, that the application of Zinc with the irrigation water should be considered only as an emergency measure. This method of application should be used only if Zinc deficiency symptoms have been observed in the field. More efficient use of Zinc can be achieved if it is placed either below or below and to the side of the seed at planting.

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