Farmers often look for simple and cost-effective ways to provide nutrients to crops. One common question raised by many farmers is whether zinc sulphate and DAP (Di-Ammonium Phosphate) can be mixed and sprayed together as a foliar spray. While both are very important fertilizers for plant growth, their compatibility in spray form needs proper understanding to avoid wastage and crop damage.
First, it is important to know why these two fertilizers are used. DAP is mainly a source of nitrogen (N) and phosphorus (P), two major nutrients needed for strong root development and overall growth. Zinc sulphate, on the other hand, provides zinc (Zn), which is a micronutrient essential for enzyme activity, healthy leaf formation, and preventing disorders like leaf chlorosis (yellowing of leaves).
The basic problem arises when these two are mixed in water. DAP is alkaline in nature, meaning it increases the pH of the solution. Zinc sulphate is acidic. When both are mixed in the same tank, a chemical reaction occurs, leading to the formation of insoluble compounds. This means the zinc becomes unavailable to the plant and settles down as a residue in the spray tank or blocks the spray nozzle. So, even if the mixture is sprayed, the plant does not get the required zinc benefit.
In simple words, mixing zinc sulphate and DAP for spraying is not recommended. It results in wastage of zinc and can reduce the effectiveness of both nutrients. This also increases labour and input cost without giving expected results in the field.
If a farmer wants to apply both nutrients, the best approach is to apply them separately but in the correct time interval. For example, DAP is usually applied to the soil as a basal dose during sowing or early stages. Zinc sulphate can also be applied to the soil at this stage, but if the field is already deficient or soil application is not possible, then zinc sulphate can be given as a foliar spray at 1-2 sprays during early vegetative growth.
For foliar spray, zinc sulphate is typically used at the rate of 0.5% to 1% solution, usually mixed with a small quantity of lime to neutralize acidity and avoid leaf burning. It is also important to use clean water and spray during morning or evening hours when temperature is not very high.
If phosphorus through foliar spray is needed, it is better to use water-soluble fertilizers specially designed for spraying, instead of DAP. These dissolve completely and do not react with micronutrients like zinc.
In summary, zinc sulphate and DAP should not be mixed and sprayed together because they react chemically and reduce nutrient availability. Instead, they should be applied separately in soil or sprayed at different times. Following proper nutrient application methods ensures better plant growth, healthy leaves, and higher yield, benefiting farmers in the long run.
