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Soil water: keeping it
Dr. Victor Martin

As of this March 30th the Drought Monitor is showing improved conditions remaining. The predicted unsettled pattern of this week may continue to help. Alfalfa and wheat continue to progress and it’s definitely time to monitor alfalfa for insects. The six to ten-day outlook (April 6 to 10) indicates temperatures well above normal and slightly below average precipitation. The eight to 14 day outlook (April 8 to 14) indicates slightly below normal precipitation and normal temperatures. A decent forecast as we head into spring planting season. Today, after describing soil water holding capacity and getting precipitation into the soil, how do we improve soil moisture?

Naturally, unless you have irrigation, you don’t control what precipitation a field receives but you can maximize the chances of it staying where it falls and get it into the soil profile. And once you keep it there, how do you keep it in the profile for crop use? Some suggestions include:

• Leaving crop residue on the soil surface and/or cover crops help slow rainfall down and allow it to infiltrate into the soil. And to keep snow in place, have standing stubble over winter.

• Minimizing tillage or transitioning to no-till or strip till if possible achieves several objectives. Residue on the soil surface serves as a vapor barrier to minimize evaporative loss in addition to keeping the soil cooler which also decreases evaporation. This also helps promote the buildup of organic matter in topsoil which increases soil water holding capacity and helps prevent soil crusting which aids infiltration. It also helps build a stable porous soil structure which leads to the next item.

• By employing conservation tillage you develop a more porous soil structure with stable aggregates containing more large pores that are continuous down into the soil. This allows for a greater infiltration rate once the soil is saturated. It also moves water deeper into the soil profile.  

• You can’t realistically change the soil texture (sand, silt, and clay) positively to increase water holding capacity but you can increase, slowly over time, but increasing organic matter accumulation in topsoil through reduced tillage, cover crops, green manures, and not so green good old-fashioned manure.

• To allow water to infiltrate on sloped ground plant perpendicular to the slope and with the contour. Especially if you have worked ground, building terraces reduces the length of slope with water flow which keeps the water, and soil in place.

• During fallow periods, keep the ground weed free, preferably through chemical control or heavy residue cover.

• If you must till, any aggressive or deep tillage should be as far ahead of planting as possible with succeeding tillage passes as shallow as possible.

Naturally there are other techniques but this provides a starting off place.

Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.