Ag Instructor Vic Martin:  Summer Crops and the Weather | Barton Community College

Ag Instructor Vic Martin:  Summer Crops and the Weather

Great Bend Tribune
Published April 15, 2018

No changes to report on the drought front except that there are indications the La Nina seems to be weakening and that could eventually lead to a return of more normal precipitation patterns.  Unfortunately it will take more than normal rainfall to significantly eliminate drought conditions.  The smattering of precipitation starting to happen is one indication of this.  Last week discussed the effects of the cold and dry on the wheat crop.  This week, let’s consider the weather and our summer crops – corn, soybeans, grain sorghum, and alfalfa.  We will take them in reverse order.

  • Alfalfa – This is a deep taprooted perennial crop.  While it uses more water than any other common Kansas crop for optimal production, it is also the most drought tolerant.  The seesaw temperatures won’t hurt it much and most of the established alfalfa in the area looks good.  The first cutting is typically mid-May and the crop is about on track except for a lack of moisture limiting forage production.  Cooler temperatures and rain will actually help control many of the insect pests common this time of year.  Any burn back of foliage by freezing temperatures will likely only be cosmetic.
  • Grain sorghum – The ideal planting window starts about mid-may for the area so there is plenty of time.  It germinates best at a soil temperature of seventy degrees.  Planting depth should be no deeper than two inches on sandy soils and one to two inches at a maximum on heavier soils so rainfall between now and mid-May would definitely help.
  • Soybeans – Fifty degrees is the low end of acceptable soil temperatures for germination although sixty degree plus soil temperatures are preferable.  Soybean planting depth should be one to two inches depending on soil moisture.  At depths greater than two inches spotty germination is common.  Unlike grain crops where the root system forms above the seed, the soybean has a taproot system forming below the seed shallow is acceptable with soil moisture.  Soybeans start to bloom based on decreasing daylength, a long night plant, unlike corn where it is based on heat accumulation.  Therefore soybeans have a wide planting window, depending on the maturity group, from early May through June but earlier is better to allow for the establishment of a good taproot system.
  • Corn – We would like a minimum average two inch soil temperature of fifty degrees and we are there.  Soil moisture is a concern naturally.  One to one and a half inches is the ideal planting depth but we can cheat to around two inches or a little over in a pinch.  Since the root system develops above the seed surface soil moisture matters.  Dryland planting should be starting or have started by now with irrigated to follow.
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