New Mexico Irrigation Scheduling for Cotton
| max root zone depth (inches) | 48 | select the maxim root depth that the crop will grow |
| Root growth coefficient inches/degree | 0.01 | The should be adjusted so that the maximum root depth is reached when the the crop coefficient reaches the maximum value . 1 or greater |
| irrigation amount (inches) | 4 | Amount of irrigation water that is applied at each irrigation. In the spreadsheet under column U this amount will be placed on the day the crop should bee irrigated. If the amount or date is different , then enter the correct amount or enter 0 for that day if you did not irrigate and then enter the amount on the day you did irrigate. |
| soil water holding capacity inches/ft | 1.5 | This is dependent on the soil type . See the soil table for value for each soil type |
| Management allowed depletion% | 50 | This is the amount of water to be taken out of the soil profile before irrigation. It is crop dependent and should be set at 50% if no information is available. See Sanders for suggested MAD. MAD=1-ASM (Available Soil Moisture) |
| Beginning root depth | 6 | This is the soil depth that contains water for evapotranspiration assumed to be at field capacity at planting. The soil profile down to the maximum rooting depth is assumed to be at field capacity. If this value is set to zero then if root grow fast enough then irrigation will not occur because the plants are getting enough water from the soil moisture in the lower depth. However, if the root growth function does not allow the root for shallow rooted plants to grow fast enough then irrigation will have to occur every couple of days. To stop this from occurring will cause some soil moisture stress but save a lot of water. This is accomplished by setting the beginning root depth at some value 6- 12 inches. |