Which irrigation system should an asparagus grower choose?
Many asparagus growers are considering installing irrigation systems when they plant new fields. Is overhead or trickle irrigation best?
Which irrigation system is best for asparagus? Unfortunately, that is not a question that we can answer, at least yet. The simple fact is that there is no definitive study that shows that one system is better than another. The Michigan asparagus industry is funding research into irrigating asparagus. Dan Brainard of Michigan State University’s Department of Horticulture has established plots to help determine first, whether it pays to irrigate asparagus at all and second whether one system (overhead or trickle) has an advantage over the other. These plots are only in their second year, and we do not yet have a clear answer.
Each system has some clear advantages for growers. Permanent overhead systems generally have a longer lifespan (about 20 years) compared to trickle tube systems (more often 10 to 15 years). This means that overhead systems can be used for irrigating other vegetable crops or field corn after the asparagus field is taken out, generally 13 to 15 years after planting. Overhead systems are also ideal for incorporating fertilizer or herbicide in no-till crops like asparagus. In dry springs or summers this can improve plant growth in the case of soluble fertilizers or weed control in the case of herbicides. Another possible advantage during harvest may be to cool the soil above crowns, which could result in better tip quality in hot weather, although this too is not proven.
Trickle irrigation also has obvious advantages. Because trickle lines are much closer to the asparagus crown, especially when buried below the crown at planting, much less water is required to irrigate fields. This should mean that growers can get by with drilling a smaller and therefore cheaper well than with an overhead system which necessarily irrigates the whole field from the surface down to crown. Even more importantly, trickle irrigation does not wet the foliage the way overhead systems do. This should result in fewer foliar diseases like asparagus rust and Stemphyllium purple spot. Since those diseases are often the most devastating pests asparagus growers face, this would be a clear advantage.
Dr. Brainard will discuss the most recent results of his research at the 2012 Oceana Asparagus Day program in Oceana County. This year’s program will be held at St. Joseph Hall near Hart, Michigan on March 8. Check the Oceana County MSU Extension website for further details.
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