Warm, dry weather can lessen some production challenges, but it clearly increases the need to irrigate. Not surprisingly, growers are currently working overtime to meet crop water demands. Some forecasts call for high water demand conditions to continue, important because many crops are entering particularly “thirsty” stages uniquely sensitive to water deficits. Therefore, as one step in overall crop water management, consider taking stock of how much water is delivered during typical irrigation events. Doing so helps compare water supplies to expected irrigation demands and prioritize irrigation across plantings if rationing becomes necessary, in addition to providing other benefits. Of course, in the big picture, crops differ in their sensitivity to even temporary periods of sub-optimal soil moisture. Just as relevant, the production cycle for each crop includes stages in which sub-optimal soil moisture has a greater or lesser impact on yield and quality. The June 28, 2016 VegNet article (https://vegnet.osu.edu/sites/vegnet/files/imce/newsletters/VegNet/6-28-16%20VegNet%20Vol%2023%20Issue%2011_0.pdf) outlined this issue briefly for cabbage. In addition to the yield and head size differences shown there, laboratory and taste panel tests revealed: (a) that irrigation program (timing) influenced cabbage flesh chemical properties and (b) that panelists could differentiate cabbage samples from different treatments by taste.
Installing and recording information provided by a flow meter is a simple, relatively inexpensive, and, importantly, direct method of measuring system flow. Using charts, tables, and other references such as the one below also helps. They remind us that irrigation system factors, especially bed or row spacing and emitter flow rate, typically set the baseline system flow rate, although actual flow rate is impacted by leaks and plugs. Leaks, plugs, etc are another reason to both include a meter in the line and check the system frequently. Ultimately, keeping and reviewing irrigation and crop records can be useful in optimizing irrigation practices as a major step in maximizing yield and quality.
Source: Knott’s Handbook for Vegetable Growers (5th ed.; D.N. Maynard and G.J. Hockmuth)