2-Herbicides Application

Transcript

Friends, now we are at the second lesson of the third week of our course about CASI. In this lesson we will cover why we use herbicide under CASI and what are the different types and applications of herbicides. We would also look at the use of the nozzle and what are the precautions that need to be taken while using herbicide.

Firstly, we look at why we need herbicide under CASI. We already know that one of the principles of CASI is that we need to do minimum tilling of our farm. We also know the benefits of CASI that it improves the quality of soil and it increases the water holding capacity and fertility of soil.

We know that when we practice zero tillage then there is an increase in weed growth. As we are not tilling the soil so we cannot get rid of the weeds. Hence the role of herbicide becomes very important.

Under CASI, minimum tillage is a requirement and if we do not use herbicide then we would have to employ manual labor at least 2 or 3 times to manage weed. This would increase our cost of production. In such scenarios, we use the medium of herbicide to control our weed growth.

In conservation agriculture we work in system mode. Now under system mode we have to take special care of herbicide and how we use it so that we can maximize our benefit. If we practice conservation agriculture without the use of herbicide, then we cannot achieve the final objective of conservation agriculture i.e. not just increase productivity but also generate income in a sustainable way and increase the benefit cost ratio. So not using herbicide in conservation agriculture will result in increased farming expenses and also increase our labor requirements which is a very costly input in today’s time.

Now we look at the different types of herbicide in terms of their effects. First we look at pre plant herbicide. We use glyphosate and paraquat when we are practicing zero tilling under conservation agriculture. Although, glyphosate is now thought to be carcinogenic. But still even today for preplant application we consider glyphosate and paraquat the best means of weed control. We control weed at the start of farming so that later it becomes easy to manage our farm.

The second herbicide is called contact herbicide. This herbicide slowly kills any plant that it touches.

The third herbicide is called the selective herbicide and it goes into the system of the plant and stops its growth and ultimately kills the plant.

In terms of selectivity, herbicide is of two types – selective and non- selective.

In terms of selectivity, herbicides of two types selective and nonselective. The selective herbicide commonly attacks only the target plant and leaves alone our main crop. On the other hand, the nonselective herbicide, once sprayed kills all the plants that are in the farm.

Now in terms of state, herbicides are of several types. Some are in liquid form and others are in emulsified concentrate etc.

In terms of applications, herbicides are divided into three kinds. The first is pre emergence herbicide and these are used within 3 days of sowing. This includes pendimethalin which is its best example.

The second is post-emergent herbicide and these are used when and plant starts growing. These have particular date of application like 2 4-D is used within 30 to 40 days in wheat crop. In maize, laudis is used within 15 to 25 days.

There is another herbicide known as pre-plant herbicide and it is used to kill annual weeds in conservation agriculture. Paraquat is an example of such a herbicide.

Now we look at nozzles. In the last class we had looked at flat fan nozzle and hollow cut nozzle. We use flat fan nozzle for the application of pre and post emergent herbicide.

Now, for the maintenance of nozzle, it is always suggested not to use any nails. We clean it using a high stream of water.

Now we discuss the calibration of the spray. If we calibrate the spray correctly, then we can use the right amount of herbicide. Three factors are important while calibrating. These are the speed of the person spraying, the capacity of the nozzle and the pressure within the spray. For the right output we have to move at the correct speed. If our speed is more than the normal speed, then our output would decrease per hectare. If the speed is correct then our output is ideal. Now, if the nozzle is outputting more liquid then required than our output will decrease per hectare. Also if there is more pressure in the sprayer machine then our output would decrease.

So for calibration, we keep in mind three things – the speed of the spraying person, the flow rate of nozzle and the pressure of the spraying machine. If the speed of spraying person is more than our output decreases and if the speed of spraying person is less than our output increases.

If the flow rate of nozzle is more than our output per hectare would be more.

Similarly, if we slightly increase the pressure of the spraying machine then there would be a similar increase in our output per hectare.

So if we change the speed, the flow of nozzle and the pressure of spraying machine then we should recalibrate the spraying machine

Now we talk about the precautions we should take while spraying. We should always make sure that the spraying person is covering his body. While spraying we should be careful that none of the spraying particles comes into contact with the eye and skin of the spraying person. He should wear a full length boot while spraying and always wash his hands with soap after spraying. Also, he should not eat anything or smoke while spraying. These are the guidelines that one should follow while spraying and thus save ourselves from the dangers of spraying herbicide.