Posts Tagged ‘wheat irrigation’

Dry Spring and Small Grain Irrigation

Thursday, April 12th, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Available soil moisture is becoming a critical issue in small grain fields across the entire state. For producers fortunate enough to have the means to irrigate small grain fields, now is the time to replenish the top and subsoil moisture supply, especially for winter wheat. Barley is much further along developmentally (most has already headed out) and matures earlier in the year than does winter wheat. Although I might hesitate to spend the money to irrigate barley that is already past flowering, I would not hesitate to irrigate wheat, which, for the most part, has not reached the heading stage as yet. In some irrigation work we did on wheat a number of years ago, we found that irrigation after head emergence tended to decrease yield potential, although only by a small amount and this decrease may have been related to disease pressure encouraged by higher humidity conditions created when irrigating. My preference for small grain irrigation is to apply enough water before heading to build the topsoil and subsoil moisture levels back to near field capacity. This should provide the water the crop needs to mature since wheat and barley are excellent at using available soil moisture.

As a side benefit, irrigation can help with emergence in the crop following the small grain crop. Without adequate early irrigation, it can prove difficult to rewet the soil, and especially recharge the deeper layers of soil, with enough moisture to adequately support the second crop if the dry weather continues.

Update on Wheat Irrigation

Friday, April 18th, 2008

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

This past winter at a Kent County Crops Masters program on irrigation a number of growers talked about their experiences with irrigating wheat. In addition, I’ve talked recently with others who were able to estimate the value of irrigation on the sandier soils in southern Delaware. It seems that many of the growers irrigating wheat on sandy loam soil types in Kent County found yield responses on the order of 3 to 5 bu/acre this past year. On the loamy sands and sands in southern Delaware, growers report a larger response in the range of 20 to 30 bu/acre during 2006. This year’s very dry spring in many parts of the state suggests that once again we will find responses to irrigation. It’s still my contention that your best response to irrigation on wheat will be when you apply a lot of water early (before heads emerge) in an attempt to bring soil water levels to field capacity in both the top soil and the subsoil horizons. Once heads emerge, you should not irrigate while the wheat head is in flower since this can lead to the development of head scab. In our limited research on irrigated wheat, we also found small decreases in yield when irrigation was applied after heading. For that reason, unless the soil becomes excessively dry, I would suggest heavy early irrigation to charge up the soil water supply, no irrigation during heading and initial seed fill, and limit the number of irrigations after the seeds begin to fill to the minimum number possible that will keep the wheat growing up to maturity.

Other than the lower than ideal rainfall totals across the region at this point, the growing season has generally been very favorable for wheat development with cool nights and moderate daytime temperatures. Temperatures have been nearly ideal for wheat. Limited rainfall and cool weather also means that very little of the nitrogen fertilizer applied to wheat has been lost so yield potential from the fertility viewpoint should be high.

Irrigating Wheat

Wednesday, March 26th, 2008

 Gordon Johnson, Extension Ag Agent, Kent Co.; gcjohn@udel.edu

Wheat irrigation is a subject of considerable discussion. Does it pay? When should wheat be irrigated? How much should wheat be irrigated? When should you stop irrigating wheat? The following are some thoughts on the subject.

  • Irrigation does not always show an increase in yield. In fact, irrigation at the wrong time could potentially reduce yields. On average, a 3-7 bushel increase in yield has been seen with irrigation looking at yield maps. At today’s prices, a 7 bushel increase would be over $60 more per acre. This must be weighed against the cost of irrigation. Fuel costs alone to apply 1.5 inches of water would be $19 per acre.

  • Wheat water use is minimal until jointing, when the plant has some height to it. At jointing, wheat will use between 0.2 and 0.25 inches of water per day. At boot and heading stages, wheat is using around a quarter of an inch a day, and during grain development through the milk stage, wheat will use about 3 tenths of an inch a day. Once wheat hits the dough stage, water use drops off considerably.

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