 This is the same old slide which we had shown earlier when we started with the topic of finding out the etic crop, what are the calculation procedures and we had said that we can do this by taking 3 different steps, we have already taken care of the first step which is the effect of climate, we had mentioned that if we can delineate the effect of climate and from the the effect of the crop characteristics then our problem will be simplified, that is what has been recommended by AFU and we have taken into consideration the effect of climate by finding out the reference, reference crop vapor transpiration, this has been done by taking into consideration the ET0, so this we have dealt with in rate length, we have looked at all the methods which are available to find out the ET0 value and we have also looked at what is the what are the data requirements of those methods, having done so let us now go on to the next step which is to incorporate the effect of crop characteristics because once we have found out the ET0, ET0 is only a reference evapotranspiration which is in this particular case the way we have considered is for grass and we have taken that into consideration because of the fact that the grass can be controlled in the sense you can control the length of the the size of the grass, you can ensure that all those factors which are influencing the crop characteristics they remain constant, so in the case of grass also the effect of the crop characteristics is taken care of but the only difference is that that effect is a constant effect, that is why we are calling it a reference crop evapotranspiration okay but that is not the ultimate aim, we have that is only a wire media that is only one of the intermediate steps, we wanted to find out the ET crop and that too for not only one crop or different crops and when you are looking at a particular area it is not necessary that you will have the same crop throughout the area, the area might be having growing various crops starting with the grain crops, the fodder crops, the they can be some tree plantations, they can be some other type of vegetable crops can be there, so all different mix of crops can be prevailing in that particular area and we want a methodology by which we can find out what is the the crop evapotranspiration for each individual crop, so to to attain that we had said that they are we can use these three different steps and we have taken care of so far the first step where we have found out the effect of climate in terms of the reference crop evapotranspiration okay. Next today we will start with the effect of the crop characteristics that how we incorporate the effect of the crop characteristics into the the evaluation of ET crop and that we had mentioned in the beginning that that is done by defining the crop coefficient, this is what is known as crop coefficient, this crop coefficient Kc what we are what we are saying is that now since we know ET not and ET not can be related with the ET crop through a coefficient which is the crop coefficient and which can change from crop to crop, we will we will look at how much it can change, how we how we find out the values of these crop coefficients for various crops and what are the factors which influence this crop coefficient. In general this is a slide which gives the overall variation for majority of the crops with respect to what you get as the reference crop evapotranspiration here on the x axis we have this ET grass which is nothing but can be used as ET0 or ET not, this is the reference crop evapotranspiration and if you compare the crop evapotranspirations of some other crops you will find that the variation is on both sides, there are some crops which are having more evapotranspiration requirements than the grass, there are some crops which are having less evapotranspiration requirements than the grass, so all this this is the line which is 45 degrees line and which shows the grass, if you have if you have any crop which is the ET crop of that crop if it is falling on this line that means is equivalent to the ET not or the evapotranspiration of that crop is equal to the evapotranspiration which is experienced by the grass. Look at this group which is the group containing cotton, tomatoes, sugar beet, maize, apple, this group has a value of ET crop which is more than the value of ET not or ET grass and that is why if you take the ratio is greater than 1. So in these crops and there is a lot of variation you have to understand at this stage that it is not necessary that one particular crop will have a specific level of ET evapotranspiration value is also influenced by many other factors. So this is this is a curve or this is a plot which shows the variation of ET grass with respect to the ET crop or different crops but there is there is a lot of scattered in this variation which accounts for many other factors which are for example the cotton of a particular area the species of cottons there can be many species of cotton which are prevailing. So when you say cotton is not that it will have a unique value of evapotranspiration it will also depend on where it is grown what is the growth period of that particular crop okay what is the showing date so all those things all those factors will have a look in a moment this gives you the overall picture what can be the variation for example the pineapple and the citrus these are the crops which are having a value of evapotranspiration much less than the that of the grass under the similar conditions here you are assuming that the conditions the climatic conditions are similar only then the comparison can be possible. This is because of the characteristics of these crops for example in the case of a pineapple the stomata the leaves of the pineapples are such that the stomata closes during the day time. So the loss of moisture through the stomata which takes place that is reduced considerably and that is why the evapotranspiration value is also influenced similarly in the case of citrus trees all the citrus trees which include the orange or all these which have the citrus qualities all these trees you will find that the leaves are waxing the formation of the leaves are such that the evapotranspiration is much lower so they are hardy trees they can survive so the species of the various crops will be influencing the evapotranspiration rate and that is depicted in this particular slide. So it is not necessary that when you are comparing with the grass is the grass is not the one which is the lowest evapotranspiration crop they are crops which are having much lower values of evapotranspiration. Now here I have tried to give you the range that how the 80 crop varies from crop to crop for some of the crops I have just mentioned that what is the seasonal evapotranspiration requirement in terms of millimetres. If you look at alpha alpha it ranges from 600 to 1500 millimetres here we are trying to look at the total value throughout the season of the crop banana 700 to 17 beans 250 to 500. So variation is a real considerable variation from crop to crop and within the crop also you will find that within the crop if you take if you divide the total season into some separate segments which we call the growth periods or the stages of the crop growth you will again find that the difference is there. So when you talk of the KC value here we come back to the KC because we that is what we are interested in the crop coefficient is something which is not a fixed factor is not a fixed coefficient it will change from crop to crop it will change from stage to stage within the crop also. So that variation is what we are interested in there will be a variation in KC from depending on the crop type KC will also vary with respect to the stages of some other factors also which will affect the crop coefficient we have said the crop characteristics is one factor which will affect the crop coefficient the crop planting or showing date now this is a factor what happens in a crop if you delay its planting the whole sequence of its growth changes it affects the whole sequence of its growth process because of the variations in temperatures because of the variation in climate which are which are encountered in that particular area. So the crop planting or the showing date might change the growth process of the crop and thereby the KC will also be affected. The length of the growing season again different under different environments you will find that the same crop might be having a different growth period. The climatic conditions how do they vary we have we have looked at the impact of the climatic conditions on the ET0 but again it depends how we are considering those climatic conditions are we considering them on the average basis or we considering them on the actual basis so those climatic conditions the variations will have some impact on the KC values which will again we will have a look at each of these factors or the effect and the frequency of rain or irrigation that means the availability of water what is the moisture availability in the soil that will influence the KC values because KC value is nothing but is a factor which is relating the evapotranspiration with some base evapotranspiration which is the ET0. So the the opportunity of evaporation evapotranspiration evaporation as well as transpiration this opportunity will be dependent highly on the availability of moisture that we have seen in the in the case of our topic where we had tried to look at the relationship between the crop the water and the soil and we have seen that how the stresses change how the moisture utilization changes with the availability and all those things so the availability of rain or irrigation water in the soil or the moisture of moisture availability in the soil will influence the KC factor also. Now here one example has been taken to highlight some of these factors this is the case where sugar beet is the crop and the KC values have been shown here for the same crop but having different growing seasons this is the sugar beet which is is grown in the autumn and spring and summer and all these 3 cases the total growth period is different in this case it takes 230 days of the sugar beet in this case 200 days in this case 160 days and this is because of the fact that there is climate is different within this for each individual case you will find that here it is depicted that how the KC actually changes when you make the water available so when the conditions are wet suppose you have given the this is the initial moisture condition this is the initial moisture level now the KC will keep on varying the actual coefficient will keep on varying with respect to the moisture availability it will keep on reducing as the moisture reduces because in that case what happens the evapotranspiration activity is influenced because of the moisture availability the moisture is not available though there the potential is there for the moisture to deplete from the soil but the crop is not in a position to make that depletion possible because of the high stress because of the deficit which is available in the moisture the soil thereby that is that is taken account of by the KC factor so the KC is the one the the crop coefficient value reduces so again if you apply this is the amount of irrigation water you have brought the the level up to a level which might be close to the field capacity level so you have applied another irrigation at this particular stage again the KC value goes up and the same continues so if you keep on applying more irrigation or there is natural rain then you will find that this KC will fluctuate with respect to the moisture availability of the soil and this is the firm line which is shown here this is basically the average value of KC because in actual practice when you are using these values it might not be possible to keep track of the actual moisture conditions you are you are trying to use a value which is an average value of KC and this gives the the variation of KC and this total growing season okay. Now in the in the other case you will find that in this particular case the the time for maturity has reduced so the same thing is also true in this particular case also in the third case also is the same trend is same but the time to maturity is much reduced because of the the different climatic conditions that happens and it happens because of the the various in this case it happens because of the the moisture availability it also happens because of the different species of the same crop are under different climates and you will have to find out the KC values which are relevant values which are which are appropriate values under those conditions that is what is the important factor which you will have to look at. Now this is again the same slide which we had looked at earlier that in the case of field and vegetable crops in general we can divide the total growth period of crop into 4 stages initial stage the crop development stage the mid season stage and harvest or the late season stage. These 4 different stages in literature you will find that these stages the data are available for most of the crops what are the various stages what is their what are their lands and if they are not available the local universities or the local research organizations which are indulging in this particular area of agriculture they will have those values. These are the values which are not difficult to get. Once you have these values the data on these basic growth periods of the crops you can develop the KC values using the various procedures which are recommended by AFU it has been found that for these 4 different stages let us first discuss only for the field and vegetable crops because the evaluation of the KC values for other crops which are having different characteristics is also different this AFU 24 which we are referencing for this particular purpose it has all these details given they have recommended the growth periods for different crops under different conditions and they have tried to cater to the total requirements around the globe and they have also given the procedure which should be used to construct your own KC values or your KC variation when you use a particular crop. So that is what we are trying to look at. Now this is the a graph which gives the average KC value for initial crop development stage for the field and vegetable crops the very first stage it gives the values which are a function of at which frequency you are making the moisture available. Let us look at the initial stage what happens in the initial stage your only activity is the activity of sowing the size of the plants will be very small by the end of the stage also. So which is the activity which is the most important activity during this period is basically the activity of the evaporation there is hardly any transpiration which becomes the part of the total evapotranspiration. So the evapotranspiration is predominantly governed by the evaporation activity, evaporation from the soil is quite obvious that the evaporation from the soil will be a function of the moisture availability in the soil whereas in the other cases when the crop grows and the land of the soil on which the crop is growing in some cases it might be totally shadowing the land. So there will be the reduction in the evaporation activity will be taking place as the crop grows the higher the canopy formation will be there of the crop and it will also depend on what is the what is the type of crop how much shading it can or how much coverage it can give to the ground but in general you can visualize that the activity of evaporation will reduce as the time passes as the you go into the next stages of the crop growth but in the beginning in the very first stage the major activity will be the activity of evaporation. That is the reason that the average occurrence of irrigation or the availability of the natural water to the rain will be the first will be the governing factor in the case of the initial stage that is what has been recommended here that in the this particular stage the KC values versus the ET0 in millimeters per day during the initial stage that has been plotted and is varying with respect to the average recurrence interval of the rain or of irrigation. Let us have a look this top belongs to a recurrence interval of 2 days whereas the next one recurrence interval and the next one is 7 days and so on this one is 7 days the next one is 10 days and 20 days okay in this case let us have a look what we are saying indirectly is that if you are making the moisture available very frequently then knowing the reference crop evapotranspiration for this a KC value will be very high value. So if you have if you have 7 millimeters per day as the ET0 value and your moisture availability is every second day you are making the moisture available either through irrigation or through rainfall as a material then the KC value will be 0.8 on the contrary if the if you are making the water available after 7 days and the ET0 is the same 7 millimeters per day then your KC value is 0.6 is low again because of the reason that the evaporation activity will be much less. So since that is the dominating segment of the ET crop so your ET crop will be much less if the moisture availability is less the ET crop will be less and that has been taken care of by this particular graph. So the lower the the recurrence interval of the irrigation or rain you will get a lower KC value because the evaporation activity will be influenced will be much difficult for the moisture to leave the soil through evaporation and thereby it will influence the KC factor so your KC value will keep on reducing okay. So using this representation you can find out what is the KC value for the field and the vegetable crops during the initial stage of the crop development. For the remaining stages for stage number 3 and 4 these are the stages when you are towards the maturity you are at a level when the crop is fully mature these stages are influenced by the relative humidity the prevailing wind. So there is a relationship which has been given it has been recommended after they have collected the data from all over the world they have recommended these values for different climatic conditions and I have just picked up some of the values just to show you that these are the tables which are available you can refer to F-A24 and I will also make the tables available to all of you all these standard tables which are available in F-A24 I will provide you a set and that can be these can be used so in this case now for barley for stage 3 when the wind is between 0 to 5 meters per second and relative humidity is greater than 70 percent you are having a value of KC of 1.05 the value changes to 1.1 if the wind speed is higher is between 5 and 8 similarly if the relative humidity was lower it was less than 20 percent then your KC value would have been higher because there is more absorption capacity in the air there can be a the activity of evapotranspiration can be enhanced and that is why that can be taken care of by a value which is a higher value of KC similarly if the wind is again of a higher magnitude then you will still get a value of KC which is higher than this value or these values also similarly you will find that between the stage 3 and 4 there is a drastic change in the case of stage 4 which is the last stage when the crop is mature is the stage which is the harvesting stage you will find that the requirement of evapotranspiration reduces drastically because the crop does not need that the moisture any further and it goes down from 1.05 to 0.25 but again there is no hard and fast rule is again a function of which crop you are talking about what are the characteristics of the crop. If you look at between barley and beans in this case the KC value is reduced from 1.05 to 0.25 whereas in this case in the case of beans it has reduced only from 0.95 to 0.85. So the reduction in the KC value is a function of which crop you are talking about what are the characteristics of the crops how much is the moisture requirement of the crop and that is depicted very well depicted here most of the grain crop crops you will find that the requirement reduces drastically. Example in the case of wheat also from 1.05 it goes down to 0.25 but in the most of the vegetable crops you will find the difference between stage 3 and stage 4 KC values they might not be that much different the variation will be very minor variation which shows which indirectly dictates the water requirements. We are looking at we have the ultimate aim is how much irrigation water you will need if the natural water is not available. So these things will will throw light on the requirements because you should supply that much as is required and that is that is what we are trying to go through in this total process. So suppose this is what I was referring to that is again I have picked up the length of growing season and the crop development stages of some of the field crops. These are the the crops which are just taken the barley, wheat and pork they have the same growing length the growing season length but they vary from if you talk in terms of the same crop but they are grown being grown in different environments then their length can also change that is what we have seen in the case of Central India, wheat is grown in November and these are the lengths of 4 stages the first stage 15 days length, second stage 25 days, third stage 50 days and the fourth stage 30 days. So the total length of the growing period is 120 days but the same wheat or barley when is grown in East Africa in the high length the month is July and the length of the different growing stages the change is 15 the same in this case but this is gone to 30 there is 65 there is 40 and the total length is now 150 days in place of 120 days which we have seen in India. Similarly in the case of beans for different areas all this is made available by AFU they have compiled this data and they have consolidated this data and that data is available. So the length of the growing season is also something which is available with you you can use that information to construct the variations of Kc. Now having done so let us look at how we proceed suppose this is this is the we have seen that if we represent the period this is the period this is the initial stage stage 1 of a specific crop any crop you can choose and then the next stage is the second stage is the crop development stage so you know the length of this stage also in terms of days is number 2 you have the mid-season mid-season stage and you have last stage which is the the late season stage. Now having known these these 4 variations which we have found that they are available for a specific area for a specific crop once we know these we can then the recommended procedure is that here we are going to find out the crop coefficient this is what we are interested in knowing that how this varies from stage to stage or for this total period of the crop how the Kc values vary. We have also noted down that the Kc value for this initial stage we are we know that there is a value which is available depending on depending on this variation which we have just looked at the initial difference in towel if we know the climate if it is rain which is the input or if the input is the irrigation then what is the recurrence interval of that irrigation which you are using in that particular area knowing that and knowing the 80 knot because 80 knot is already computed using one of the methods which we have recommended. So knowing the 80 knot and the recurrence interval of the moisture availability we can read out the value of Kc during that initial stage. Suppose this is the value which we have obtained and this value will be you can say that this varies from 0.3 and in between this is the scale which is used so on that scale you find out what is the value of the Kc during this initial stage and we can assume that this variation is throughout this initial stage the Kc value remains similar or remains same during that stage. There is assumption which is made here in constructing this variation. Then we come down to the late season stage in the late season stage we have again seen that for the specific crop which we have which we are looking at we can use the information available and find out what is the value of the Kc values for the specific environment if we know the R H minimum if we know the winch speed we can find out which is the value which is the relevant value for stage 3 as well as stage 3 stage 4. So those 2 values are known and we can draw them in the form of those 2 points this is 1 point and in the case of the stage 3 there is another point which we can say that this is the point. The values which are the corresponding values which we can read from that table so these 2 values are written down. Now the recommended procedure is that we draw a line parallel to the x axis from that point which is for the mid season stage. So we draw a horizontal line to that point for the total mid season stage and for this is the stage, total stage and then we join these this is the end of the initial stage we join this and this and on this side we join this and this. So this Kc value is plotted at the end of the 4th stage and you join the point which is corresponding to the end of the mid season with that point. Now this gave you a variation and then you can even because you know that the variation is not occurring in this manner there is a abrupt we have some abrupt changes which cannot occur in nature. So there has to be some smooth transition from one stage to another stage and you can draw approximately a shape which is a smooth between these points or you can even this is the variation which you can take as the representative variation of Kc value. And this can be used this can be constructed for any crop which is the vegetable or the green crop and you can use these 4 known values. What we are assuming is that between this stage initial stage and the crop development the mid season stage during the crop development stage there is a variation of Kc value from a known value of Kc during the initial stage up to the mid season stage and we are trying to use that because this is a very steep change and during the other periods we have some representative values available we are making use of those values to give a uniform variation which can be used now to find out how the crop, crop up or transpiration will vary from stage to stage within the same crop. On the contrary if you want to use a mean value for the whole season of the crop even that can be done by taking a representative value which is a mean value of this variation but it depends on what is your requirement. For example if your requirement is to go in for the design of the irrigation system where you are looking at the values which are to be used on the average basis whether that time when you are going for the design you have to look at many other factors one major factor is the size of the distribution system. If you try to cater to all the requirements in terms of the extreme requirements you might find that your size requirement of the carrying or the carrying capacity in the form of carrying capacities of the channels or the canals will become so huge that it might not be economically viable. So if that is the requirement then you might have to look at some average values you also have to bring in the risk factors. Do you want to take care of the extreme values always which means that even those situations which are experienced very infrequently may be once in 10 years or once in 15 years if you take care of those extreme situations, extreme climatic conditions then you had it because then the requirements of from the the the system requirement point of view they will become very huge whereas if you are interested in utilizing this information in deciding what are the actual requirements in terms of the scheduling of irrigations. When you try to find out what are the requirements at a particular location of irrigation then you might need the actual values of Kc how do they vary from time to time because when you talk of irrigation requirements how much water is needed you are talking in terms of the known climatic conditions. Are you here and what what we are saying is that when you are giving the irrigation are you at this location in time or are you here? If you are here your requirements are very small in comparison to what will be the requirement when you are here. So that is what the the total business of scheduling is that how much require requirement of water is there, how you are going to supply that in what quantities at what timings that we will come to. At this stage I thought it would be better if we can put some some thinking in terms of how we are going to utilize this or what significance this Kc variation has in terms of the water management, okay. Any question? Thank you then we will stop here and tomorrow we will.