Global weather modeling is a very complex mixture of art and science, and it’s impossible even to make firm near-term predictions about temperature and precipitation changes in the US, but most climate models agree that precipitation, when it does occur, will be more intense nearly everywhere. This is a key factor to consider, since infrequent but very heavy rainfall is not helpful for most agricultural crops, given that most of it will simply flow past your crops and down to the nearest creek.
Ultimately, even if rainfall in your region has typically been gentle and has arrived at just the right time of year, that’s almost certain to change. In fact, even in areas where there’s been a longstanding drought, things can change rapidly and it’s critical for farmers to be prepared. In late October last year, California’s Sacramento Valley suddenly punctuated a 212 day stretch of zero measurable rain with an overwhelming 5.44 inches of rain within 24 hours, brought in by an atmospheric river fueled by warming global temperatures. And yet, despite weekend rainfall totals that topped 16 inches in Mount Tamalpais, just north of the San Francisco Bay, the drought was not over. Farmers who were prepared to capture even some of that deluge found themselves in an enviable situation. This kind of future planning is the mark of drought resilience and it’s time to take a good hard look at where you stand. This isn’t a comprehensive list of questions, but they are useful in considering how an irrigation pond could fit into your overall water management strategy.
Is a cheaper source of irrigation water available?
If you’re lucky enough to live in an area that is not experiencing the pressure of water scarcity, you may have multiple options for meeting irrigation needs, and that may make investing into reservoir construction less appealing. Keep in mind, though, that even if your region has plenty of water, neighboring regions may find themselves purchasing from the same supply you’re counting on. Whether those supplies are eventually overdrawn, or you’re simply priced out, it’s unwise today to count on stability. In that same reasoning, it’s the responsibility of all farmers and landowners, as stewards of the land, to make choices focused on healthy, sustainable practices.
Is there an existing farm pond that could be adapted for irrigation?
Some farm ponds are well suited to serving as an irrigation reservoir, a settling pond, or some other part of a tailwater management system. Consider the location of the farm pond compared to your crop land before anything else. Most other characteristics, including storage volume, can be adjusted if the pond seems like a good candidate.
Is there a suitable reservoir site close to the field?
If you don’t have a ready-made solution in the form of a farm pond, consider where you might construct a new reservoir. It’s fairly easy to build a reservoir along the banks of an existing stream, but if water is scarce, you’re likely to spark some concern about drawing from the surface waters. It’s probably better to identify a centralized location with access to a maintenance road and electricity. If you have an obvious suitable site, you’re in good shape, but remember that even if you must sacrifice an acre or more of productive land in order to reap a healthy harvest from 100 acres, it may still be the best solution. Especially if the choice is between harvest or no harvest.
What is the irrigation method?
If you’re using a highly inefficient irrigation method or old, poorly maintained equipment, it may be wiser to spend your budget on upgrading those elements than digging out a new source of water. While surface irrigation (flood or furrow) is the best choice for some crops (rice, for example), it is extremely inefficient for most. The same is true for high pressure irrigation systems using water guns or impact sprinklers. Unless your crop specifically demands that kind of water delivery, the use of low-pressure sprinklers positioned no more than a foot or two above the soil surface, or (even better), drip irrigation delivered directly to the root zone of your crops, is the best way to make sure the water you withdraw from the system is put to good use.
What are the potential yield and revenue increases from irrigation?
This may require some tricky prognostication, but you may be able to estimate, based on previous years, how high your yield could be assuming that your crops received the optimal amount of water throughout the growing season. Compare that to the yields you get when there are even a couple of dry weeks during a normal growing season. Consider, then, how demand (and prices) might quickly rise in a year when crop losses may have spread across a region. Depending on your situation, you may even need to consider potential yield and revenue against zero -- or the amount you would realize with no water available.
