2014 Southern Rocky Mountain Agricultural Conference recap

Artesian well Dutton Ranch, Alamosa 1909 via the Crestone Eagle
Artesian well Dutton Ranch, Alamosa 1909 via the Crestone Eagle

From the Valley Courier (Lauren Krizansky):

Radishes and turnips are saving Valley water.

Rio Grande Water Conservation District (RGWCD) Subdistrict No. 1 Program Manager Rob Phillips said on Thursday during the final day of the 2014 Southern Rocky Mountain Agricultural Conference he was confident producers with green manure in their crop rotations are utilizing irrigation water more efficiently.

At first , he said, the RGWCD was skeptical of 2013 potato circle pumping numbers because they were coming in very low, around 13 to 14 inches versus the average 15 to 20.

“But I can see why,” Phillips said to a full audience in Monte Vista’s Ski Hi Arena. “It (green manure) is building the soil.”

Planting green manure, also known as a cover crop if it is not incorporated into the Earth, is similar to placing an umbrella over the soil. The crops offer protection from water stressing erosion and weed growth, making the soil stronger to combat disease, insects and other environmental challenges through organic recycling and nutrient transfers.

These water saving crops include legumes, grasses and root crops like radishes and turnips, and green manure mixes of all kinds are showing up more and more in Valley crop rotations in response to the drought. During the growing season, living green manures retain soil moisture when crop transpiration rates are greatest and rainfall is seasonally at its lowest.

Residues left over from killed and incorporated green manures increase water infiltration and reduce water evaporation from the soil surface, specifically in no-till planting, and allow conservation tillage systems to provide moisture that would otherwise be lost through evaporation. Covering the soil with green manures also reduces crusting and subsequent surface water runoff.

RGWCD Manager Steve Vandiver agreed on Thursday green manure is working to reduce the amount of Valley water pumped, and that it is an option producers should consider to meet reduced pumping goals.

“It’s a finite resource,” said Vandiver about the pivotal role water plays in the Valley’s economic structure. “If the aquifer goes away, you are going to be taken down with it… Be thoughtful about reducing your pumping overall. Let’s do more than required in these drought times.”

There are a variety of ways to incorporate green manure into traditional crop rotations .

In the Valley, summer green manure crops are often grown in time with cash crops and are irrigated to reach desired stages of growth. Some Valley producers are planting green manure crops in the fall, and their growth is subject to timing and rainfall once irrigation is shut off for the season. Although they are at the mercy of Mother Nature , non-irrigated green manure crops emerging before winter sets in are providing valuable biomass that assists water retention, prevents soil erosion and contributes to a healthy soil structure regardless of their size. In addition to the increasing green manure rotations in Valley fields, studies revolving around the most appropriate types of green manures for the area and their subsequent effects on nematodes in potato fields are also growing.

Agro Engineering agronomist Patrick O’Neill presented data at the conference on an intensive Colorado Potato Administration Committee (CPAC) sponsored test study looking at 500 plots containing 97 green manure varieties and/or mixes. The study’s goals, he said, include further understanding how green manure crops lend to water savings, biofumigation, weed suppression, nutrient recycling and overall soil health, and whether they will work for animal grazing or hay.

“Water limited irrigation systems mean there is more ground left out of cash crop cycles,” O’Neill said. “Cover crops can be used as a tool in the interim.”

He added, “Your farm’s situation is unique, and each field where cover crops are being considered should be addressed individually.”

During the 2012 Southern Rocky Mountain Agricultural Conference, the Natural Resources Conservation Service (NRCS) reported green manures use less than 17 inches of water a year, particularly when sordan grass is incorporated into the crop rotation. Green manures also proved to lower erosion rates and water use in their studies.

More Rio Grande River Basin coverage here and here.

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