 practices are due to the local conditions and we had left with looking at the effect of changing environment because of the irrigation coming up in that area that at the time when we are collecting the data the micro environment or the micro climate was different than the climate which has been obtained after the project has come into picture. And we have seen that the through one example that whenever there is a dry condition whenever there is a condition where you have arid climate, semi arid climate and you have the areas irrigated areas surrounded by the fallow areas which are dry areas which are not irrigated areas then you will have the the advection effect, the advection will be uhh experienced and because of that you will have the conditions looking at the general wind direction. Now if you look at the windward side the starting edge of the the windward uhh uhh side of the field will have the cloth line effect whereas subsequent to that you will have the oasis effect. The case of oasis effect what it means? It means that the the conditions have become such that the evapotranspiration has reduced because of the fact that the air mass which has which has passed over the or which is passing over the irrigated area is is becoming cooler and is becoming more humid. So because of that its its capacity to evaporate or its uhh capacity to evaporate will reduce and therefore we have also looked at that as a correction you will find that if your if your areas are very large the irrigated areas are very large the net effect will be that you will have to put a correction factor which is less than 1 because of the the enhanced oasis effect. So that will be the end result that will be the end result uhh in terms of reduced value of evapotranspiration than what you have observed when the conditions were uhh such that you were you were using the data on small patches of irrigated areas which were surrounded by or which were followed by the the the the the follow areas or the areas which are not irrigated. So that will make a difference of may be 5 to 10 percent and you can put a correction factor on the the crop coefficient. Let us look at some other other effects uhh which can be which can be taken into consideration the effect due to the soil water. The level of uhh available moisture or the level of moisture which is prevalent at a particular time that will also influence the evapotranspiration activity and that is what is shown here that it also depends on what is the what is the condition of the climate. The climatic conditions will also influence but assuming that the climatic conditions are uhh not very different than the factor which is influencing the other factor which is influencing the 80 crop will be that what is the what is the type of soil. For example if we if we assume that we know the type of soil because ultimately the the moisture holding capacity or the way the moisture is held is a function of the soil characteristics as well. So if we if we assume that the soil characteristics are known then we we know by now that the moisture depletion or the moisture deficit which is being created up to a particular level you might be in a position the the root system might be in a position to extract the moisture without any problem but when the the tension increases then the evapotranspiration activity will also be affected. In general the 80 crop is not affected up to a stage where the atmospheric tension is close to 1 atmosphere and at that stage there is a stage for different soil types for example in the case of clay that stage will be attained when you when you reach a level of 30 percent of total available water, kw is total available water and in the case of loam this level of 1 atmosphere will approach at a station where you have extracted around 40 percent of the total available water and in the case of sand up to around 60 percent of the total available water. So these are the indicators these are the indicative one you you will at least you can now visualize that how much moisture is available in in fact without influencing the the evapotranspiration characteristics or without reducing the evapotranspiration in a particular crop. Let us have a look at this variation on some actual case where so if you mean 80 cotton millimetres per day this mean 80 cotton is between the period between the irrigations what is the mean value of evapotranspiration? On this side if you irrigation interval let us say that we have the irrigation interval varying from these values and so on and on this side the scale is sometime something around. How the irrigation interval influences the 80 crop? In other words what we are saying is that if you are applying the water more frequently then what will be the effect on the 80 crop then if you will apply the water at a larger interval. So for example in this particular case it has been observed that when you are applying the water uhh 80 cotton is 6 millimetres per day. As long as you are applying the water at a reasonably large interval also it is not making much effect only after uhh if you go beyond interval of around 18 days there is making some impact on the 80 crop whereas if this evapotranspiration is other extreme you might find that in this particular case might be having something of this nature. Even if since the evapotranspiration level is very high even if you apply the water very frequently you will find that in general the if you would have applied the water at the desired rate then the evapotranspiration, the potential evapotranspiration could have been 14 and there is a maximum which it there is a peak consumptive use rate of the peak evapotranspiration whereas because of the fact that you are applying the irrigation at a longer intervals the evapotranspiration the actual evapotranspiration has reduced. So you also know by now that the evapotranspiration is directly related with the the ultimate yield of the crop if if the crop is not in a position to evaporate uhh or evapotranspire at the desired rate it will have the impact on the ultimate yield, okay. So in in this situation your yield will be affected if you are not supplying the moisture at the proper rate similarly in the in the intermediate situations you will find a similar effect that the effect might not be as much as in the case of a situation where your evapotranspiration was very high. The is is basically the rate at which the deficit is being created that is going to influence what is the rate at which you must replenish that deficit, so that is what is depicted in this particular case and for the other cases also it will be slightly more but again there is some impact which which shows that we are we are trying to basically bring in uhh some other uhh factors that when we go in for the designs we have to ensure that we we know these relationships we know what is the impact of delay in the moisture supply on the drop yield and those things will have to be incorporated. Those things will have to be looked into for proper management of water. Now as far as in this particular situation uhh depending on uhh the the the actual level of your evapotranspiration the factor which has to be incorporated will be dependent on what is the what is the actual practice you are adopting, what is the actual uhh irrigation interval which you are taking into consideration and on that basis you can you can incorporate the the effect or the correction factor on the the Kc values, okay. The Kc values will also be influenced if your evapotranspiration is not take place at the at the desired rate that is what is happening here in this case that is very very essential to understand that if you are supplying the moisture at the rate which is the desired rate in this case this is the desired rate then you are you should have been in a position to get the evapotranspiration at the same rate but since you are applying the irrigation at at higher intervals in other words what is what is happening is that you know this is your the total available moisture, total available water out of this you can only only this much can be extracted this is what can be extracted by the the crop system without any ET crop is not it. So if you if you keep this much moisture in the soil then the ET crop will occur at the potential rate. If you reduce now what happens when I supply the moisture at a at a larger irrigation interval the irrigation interval means that you are supplying you are replenishing this deficit which has been created if if it takes it takes 5 days to bring down this moisture level to this level which is the level where up to which you do not have any effect on the ET crop if it takes 5 days if I wait for 3 more days if I make the interval 8 days then this soil is not having that much capacity to absorb the moisture to be serving the plant for 8 days and that 8 days limit is on the basis of what is the rate at which the moisture is getting depleted that is the ET crop that is dependent on ET crop. So if your ET crop is high it will mean that you will have to replenish the deficit which is created the deficit will be created in a relatively smaller period and unless you replenish that deficit after those many days you are going to have problems your unit is going to be affected. We will come back to these all these concepts later also when we will go into the scheduling at this stage I think this much is sufficient to know that all these are the additional factors but at the same time let me let me point out at this stage that these factors which we are discussing the local factors or the factors which are dependent on the local conditions as well as the agricultural practices this is not going to influence very drastically the ET crop the the percentage up to which this might be influenced unless there are some specific very specialized conditions you will find that the percentage will be the order of magnitude will be around 5 to 15 percent but the same time in some situations it becomes quite very major factors and there can be a situation where it can be ready detrimental if you are not taking care of the these impacts. Let us now go to the ground water ground water is another condition which will influence the the KC values or you can also say that it will influence the evapotranspiration activity why because in the case of the ground water the level at which the ground water is available if you have if this is your ground water is somewhere in this at this level this is the ground water level depends what is the what is the depth ground water is in comparison to the ground level it also depends on which crop you are growing what is the the the root system what is the effective root zone so if the effective root zone is this much in some cases it might not influence the crop that case is dependent on the soil type because how much how much this ground water influence this zone is the function of the capillary characteristics of the soil. So in some cases if the soil is is a light soil the soil is sandy then the situation is not that bad in that situation the capillary zone will be very small and you might not you might feel that in this particular case if the ground water is somewhere here it might not influence the root zone whereas if you have the heavy soil it will influence the root zone but in what way the this ground water in what way it influences the evapotranspiration there are various items which will one is that you will have the soil in this area will be its water content will be higher will be wet soil and that can create problem in terms of the agricultural operations for example if you want to use the the land the land preparation if the water content is very high the land preparation cannot be done very well because you cannot you cannot do many operations on the soil if it is very wet the water content is very high. Secondly you will also find that the wet soils they they do not even under the the conditions when the energy is available they get warm very slowly. So because of the slow warming you will find that the delayed germination will be there because for the germination to take place the the temperature in the soil has to reach a particular level. So there can be delay in the germination and preparation is another situation where you are having problem in terms of the ground water availability. The prompt plant development can also be delayed these are some of the factors along with this you will also find that there can be problems due to the variation if the water is if the moisture is always available in the soil at the ground water level the ground water table is quite close you will find that the pore spaces will be always filled up with water and the aeration can be a problem. There are if you look at the crops there are many crops which behave differently under these conditions of high ground water availability and they have been divided into the three different categories those crops which are high tolerance towards the ground water, medium tolerance and those which are sensitive crops. The ground water is at 50 centimetres these are the crops which are having high tolerance sugarcane potatoes broad beans and the medium tolerance crops are sugar beet, wheat, barley, oats, cotton, sensitive crops are maize and tobacco. Similarly under the waterlogged conditions the waterlogging conditions means that the ground water is even still higher under those conditions the rice will have strawberries, grasses most of the grasses plants these are the high tolerance crops whereas the other extreme is the peaches, cherries, olives, peas, beans. So the characteristics of the crops will have to be looked into when you have these situations where the ground water is very high is quite close to the root zone and as I have told you that is also going to be a function of which soil you are dealing with. So in this case here the minimum depth of ground water table this is a general thumb rule which has been suggested here if you have sent any soils the rooting system or the root zone depth plus around 20 centimetres is the recommended depth up to which the ground water table should be beyond that in the case of loamy soils plus 40 centimetres in the case of clay soils plus 80 centimetres. If you have these conditions prevailing then in general you do not have to put any correction factor. If your conditions are violated then you will have to look into the greater depth which crop you are talking about how much it will be influenced because of the close proximity of the ground water table and that effect has to be taken into account. Item which we like to look at is salinity. Salinity affects the evapotranspiration activity in many ways one is that it exerts osmotic pressure. So because of this the root system will find it very difficult to extract the moisture. The salts which are available their osmotic pressure is much higher and that will create the conditions where the levels which you are discussing which we are saying that in a particular soil the level of extraction by the root system we have defined those levels those levels would not be valid anymore if you have the saline conditions then it will also affect the physical characteristics of the soil. The structure of the soil can be affected it will also cause toxicity and affect the growth. This toxic conditions can be harmful to the crop development and salinity can from that angle it can influence the crops and once the crops are influenced then you have the influence on the evapotranspiration acts as well. One way to offset this particular situation is to keep the level of moisture which is available at any time in the soil at a higher level. With the high moisture levels these effects are reduced. So there is one way of handling that situation then there are other ways by reducing the salinity or by even doing the leaching process. Leaching is the process in which you use lot of water to flush the salts which are harmful salts from the soil to a level much lower than the root zone system or the root zone depth. So you apply lot of additional water on the surface and that water dissolves the salts which are which are the problematic salts. Those salts are taken to a level in that case the groundwater table has to be much lower and in case where you have water logging problems you cannot do that. But in those areas where the rainfall is quite high the leaching is automatically done whenever you get lot of rainfall that is is being the leaching process in a natural manner but in those situations where the rainfall is not excessive you might have to use the rainfall the irrigation water sorry the irrigation water not the rainfall you have to use the additional irrigation water and that becomes the additional requirement of irrigation is known as leaching requirement which will again when we look at the total requirement when we consolidate the requirements of irrigation we will come to that leaching requirement also but that is one way of reducing the salinity but in general the ETC value or the crop rubber transpiration is not chained unless you are certain that the salinity is creating a problem or is creating some effect on the growth of the plant. So unless the growth is affected if there is some level of salinity you might ignore that there is no connection which is made on the KC value, correction is required only when the the level is such that it affects the growth of the water and crop yield. This is another aspect which we have to understand then the crop production the timing and duration of water shortages we have slightly discussed in the earlier part when we were looking at the soil water availability. This concept was this protein that when you are making the water available at what time you are making the water available and how much you are making that water available those two things are going to decide what is going to be the crop yield ultimately. There are situations where the deficit which is being created in the soil the timing of that deficit is also very important because of the fact that the growth stages of the crop there are some sensitive growth stages than the other stages which are which are less sensitive. So if you create a deficit in a stage which is less sensitive it might not have very detrimental effect on the ultimate yield than the other situation where the growth stage is very sensitive and if the deficit or if the conditions are deficit conditions at during that stage if that happens then you are going to have problem then the impact on the ultimate yield is going to be much larger. That is shown on the using the actual data let us plot actual data of this is from non forage that is between yield as percentage of maximum yield that means 0 to 100 percent what is the actual yield as percentage of the maximum yield which can be achieved in that crop. On this side is the ratio of actual 80 crop maximum 80 crop. The maximum 80 crop is that situation where which will be attained when you are supplying the moisture as much as is required. So if you plot this for non forage crop plot it some this is the variation now this area this plot is a plot which is showing the mean variation which suggests that if your actual 80 if your actual evapotranspiration reduces then the yield will also be reduced accordingly and the yield reduction is in this particular case the yield reduction is looking to be proportional but is not always so it depends on many of the factors it depends on where those deficits are created in the total growth period of the crop. This dotted portion is showing the variation that in general for different types of deficits for example if you had created the deficit in a stage which was very sensitive stage then in that case you might find that even if you had created a deficit which was not very high deficit but the the impact which it made on the ultimate yield was very high in this case but look at this for example let us say that if you are somewhere here now your deficit creation is the actual 80 is quite close to the 100 percent level but still the amount of yield reduction which has which it has done it might be quite large in comparison to the other situation example if you are somewhere here this is the the yield percent as percentage of the maximum it has reduced by around 50 percent whereas if the stage was some other stage the same thing has been found that there is hardly any impact on the yield for example if the if you are looking at this extreme of the the graph you find that there is hardly any any difference in the the yield when the same deficit was created in another stage so this variation this scatter of this total area which has been shown here that proves that point that is not only the deficit the level of deficit which is important but is also important that that at which stage that deficit was prevailing similarly for some other crops also for example in the case of sugarcane the plot is something of this nature scatter is this is the same both the scales are same and on this side is the ratio of the the actuality to maximity and this side is the the yield as percentage of yield maximum yield. If you look at this this particular area belongs to the the situation where you have created this deficit in the lead growth period and this side when the deficit is created in the actual if you are creating any deficit in this period which is more sensitive period than the the lead growth period then you are getting more for the same for the same level of 80 reduction you are getting less amount of yield or the yield reduction is much lower this area of relationship between the crop and the yield reduction is a very vast area and it has been treated separately in another of your paper, paper number 33 the yield response to water so that is a very elaborate explanation on all these factors how this yield reduction is taking place and what are the various characteristics of the crops on which it is based on. Let us come to the other factors other conditions which can influence the the ET crop and what is the method of irrigation? Which method of irrigation you are using? They will also make some impact on what is the the evapotranspiration or what is the influence on Kc value and what way this can this can influence the Kc? Again the the the major factor which will influence is the way the moisture is being made available because these methods so far we have not discussed what are the various methods of irrigation we will be very soon discussing those but in general to tell you that there are methods which are known as surface irrigation methods which use the concept of the gravity flow and sometime they are also termed as flooding method that there can be some change in nomenclature but what we mean by that flooding is that you are making the water available on one side of the field and it flows under the gravity force to the the downstream side of the field then there are methods like sprinkler irrigation method to use the sprinklers and the water is sprinkled over the the area in which case it will wet the plants also whereas in the case of surface irrigation method the that irrigation those irrigation methods would not wet the the foliage of the plant the canopy would not be touched even. Then you have the drip irrigation method in that case you are using the drippers and you are you are making the area which is providing the moisture to the the root system you are making that area reduction in the the moisture requirement can be made so these are the major these are the major methods now in these all these methods has been found that ultimately these methods do not make much difference in terms of the the evapotranspiration requirements unless they are in in some case for example in the case of surface irrigation methods since you are wetting the total soil is felt that it might be more water consuming method but is not so because in the case of sprinkler irrigation you might be reducing the amount of moisture which which has to be supplied on to the the the area or you might be in a position to have a better control on the irrigation method because you can operate the system anytime you feel like you can operate it for any period of time as desirable whereas in these methods you cannot do that because there is a requirement that the water must flow from the upstream end to the downstream end and that requirement has to be fulfilled so as to provide a uniform depth over the whole length of the field but in this situation since we are putting the water from the top the the crops get wet and it enhances the evaporation the evaporation is much larger all that water which remains on the the leaves that gets evaporated the evaporation losses increase then there are some losses which are spray losses which are because the wind the water might go to some other areas where is not intended to be applied on so that can be another loss in in top of the total requirement that requirement remains almost similar. There can be some saving in the case of drip irrigation methods so from these point of views the method of irrigation can make some difference but not very drastic difference you have to look at the other conditions other prevailing conditions if you are looking at the sprinkler irrigation how much is the the wind influencing the irrigation activity so all those things have to be incorporated and that is what I think at this state we can only just mention about those those variations because of the irrigation method. Then the cultural practices these can also influence this plant population tillage mulching and the provision of wind breaks in the case of fertilizer it will only influence the evapotranspiration if the salt the desired salts in the soil are not available so if in that situation unless you supply the fertilizer unless you apply the fertilizer from outside as additional nutrition which is desirable or which is required it may not have any impact because if the natural salts are available then the fertilizer might not have any impact. So you have to look at what was the condition of the soils with respect to the condition of the soil only you have to look at these this particular factor. You can also to certain extent in even now consider where the salts are where these salts are available are these available beyond the root zone depth or they are within the root zone depth or are you is your irrigation method such that is flushing the salts beyond the root zone depth or even if you have supplied the fertilizer is it flushing the fertilizer beyond the root zone depth if that is happening then that means there is some is going to affect the evapotranspiration activity. So only from that angle that since it is affecting the crop growth it might affect the root zone the evapotranspiration activity as well. And the plant population is not a very major factor it will make some difference in terms of the evaporation because if the plant density is high then the crop will cover the ground and only in the beginning when is the initial stage you will find that evaporation will be influenced to certain extent but in the later on stage when the crop coverage is going to be there anyway there is not going to make that difference also in the evaporation activity. So the evaporation activity is the major activity which is going to be the evaporation from the soil is going to be influenced in this particular situation. The tillage is the process in which you just disturb the top soil for various reasons one is the weed control you want the weed to be removed the other is to change the soil structure 3 times the soil gets sealed the top soil gets sealed because of the impact of the rain drops and that sealing process will change the structure it might seal the pores and that sealing process will influence the infiltration ultimately and since the influence the influence of infiltration will be to reduce the moisture getting absorbed into the soil more of the water which is going over the soil will be going as a waste as a runoff very little amount will be in a position to go into the get into the soil and thereby get absorbed. So from that angle tillage can make some difference if it is rough weed around and if going in for the tillage practice you might be able to influence the weed and thereby reduce the evapotranspiration. Similarly the mulching in many situations people feel that through the mulching what is mulching first of all mulching is the process in which you let the waste the crop waste be into the soil and remain there so that it can it can influence the things like the rain drop impact can be reduced you also want in some cases to reduce the evaporation from the soil but it has been found that ultimately there are some advantages of mulching but there are at the same time some disadvantages also it is not always true that through the mulching you will get the desired effects which you thought you will be getting for example the disadvantage one of the major disadvantages that it creates the similar problems like the close proximity of groundwater it will make the soil remain wet most of the time it will also induce many diseases those can be because of the mulching and because of the additional foliage being made available on the top of the soil so that can be there can be some impact of mulching it can be taken into consideration wind breaks can also be influencing the the ET crop it has been found that the wind breaks there is a there is a thumb rule that the height of the wind break which is being used will be deciding how much will be the influence of the wind break in the windward direction up to which extent it can influence is around 25 times the height of the wind barrier that wind barrier can be in the form of trees or it can be some artificial wind barrier also but the influence is something of the similar nature that assuming that if you are providing the wind barrier what it is doing the other climate it cannot change it can only change the the wind speed it can just reduce the wind speed for example if this is a barrier and you have the crops here this is the wind direction now there will be a extent up to which you will have the you might save this this particular area from the wind which was which was prevailing wind but the other other parameters remain same so if there are some areas where wind direction or the wind speed is going to make lot of difference in terms of the evapotranspiration activity that can be influenced so with that we will close this chart here we have looked at all the aspects of the evapotranspiration requirements how we compute those requirements and what are the various methods what are their class points what are their data requirements and if there is any question I can respond.