Saving water in agriculture
Saving water in agriculture is possible. There is a few changes one has to make. Firsty is reduce cultivation,second get stover and mulch on the soil, thirdly is to get the plant variety right, fourthly is plant population which go together with plant variety and then last but not least is reduce chemical fertilizer and here especially nitrogen.
To reduce desturbing the soil is the priority.Every time a discing or tine operation loosen the soil, 25mm of accumalated rainwater in the soil evaporate. It can be more in dry hot conditions. Even when planting the soil must be desturbed as little as possible. To illustrate this is the case of a farmer in Australia who increased his yield on wheat by using a disc which opened the soil 1cm against a narrow tine which opened 4cm. The increase was 2 t/h in an area which only get 200mm of rain per anum.
A mulch or stover cover is obvious as it reduce evaporation as it is educing windflow over the soil. If stover can be left standing, like in the case of wheat, it is even better.I know it is practice to disk it in but then you loose the stover due to oxydation. I will explain more about that in a next article.
Planting the most suitable variety for your area and rainfall is obvious. Reducing the plant population can help as maize yields of 14t/h has been obtained with 25,000 plants /h. Spacing is not a problem as most planters solve this problem in the row and row width can de adjusted to need. This very high population which is the latest recommendation can work under irrigation but not in a dry year.
The last factor is chemical fertilizer. P and K is usually not the problem but the Nitrogen. It is opening the stomata on the leaves which increase transpiration and can increase the water consumption up to 80%. This is easy to illustrate by adding extra N and see how quickly the plants wilt.