Irrigation Optimization Analysis
Analysis of yield data can be tricky given the number of things that can influence yield. Agronomy, timing, drainage, fallow management, weather, farming practices and field history just to name a few. While there are influences hard to manage analysis of yield against base layers such as soil and terrain can still build valuable knowledge about variability.
An important factor to consider. While its expected to improve yields ever year the main contributor to overall yield being high or low yielding is climate. Spatially however there are optimums at the farm level that are trying to be achieved in all soil and terrain types. Optimizing these management zones on a year to year basis is a critical management methodology that should be considered.
The screenshot below of PCT Compare has cotton yield overlaid onto soil zones derived from an EM survey. Low EM zones are typically lighter soils, lower water holding capacity and lower sub soil constraints. Higher EM values typically represent higher clay content and therefore higher water holding capacity and increasing sub soil constraints and sometimes salts such as chloride.
In the graph below the trend is – as EM increases the yield goes down. In this field soil testing has shown these areas are heavy clay, salt effected areas. The blue line indicates the area of each zone. The peak in the blue line on the orange zone indicates the irrigation management for this field suited the zone of the highest area because its the highest yielding. However, this isn’t spatially perfect because the next highest yield zone is the red zone and is much smaller than the yellow zone. There is a light green line showing the optimum and at the bottom right corner which is hard to read there is a financial loss assessment. This tells us that had the zone been optimized this field would have return about $70/ha. IN the scheme of things this is about as good as it gets.