Managing Dry Beans in Dry Years
Dry beans requires less water for optimum production (16 to 20 in. of consumptive use) than most other field crops grown in Southwestern Colorado.
Dry beans (mostly pintos) are an important crop in SW Colorado and are primarily grown under dryland conditions. Dry bean production was substantially down from 2000 to 2002 due to drought. Growers asked numerous questions about whether to grow dry beans in 2002 and how to manage the crop to lessen drought effects. In hindsight, the answer would have been not to plant any dry beans (in most cases) in SW Colorado in 2002, unless there was the potential for supplemental irrigation. However, since weather is hard to predict, bean growers need to have alternate plans for dry years like 2002.
Dry bean planting in SW Colorado usually coincides with the driest period of the year, thus adequate soil moisture at planting is critical to ensure good germination and stand establishment. Depending on the variety used, dry beans should be planted as soon as possible after the likelihood of a killing frost has passed. In SW Colorado, this usually occurs after May 25th, Planting early, for instance, during the first or second week of June will ensure that the crop is mature before fall frost hits.
Bean planting may be delayed when there is not enough moisture in the seedbed to germinate the bean seeds. Planting dry beans in dry soil in SW Colorado is risky given the low probability of precipitation in June. Furthermore, soils in the region tend to form a crust after a rain, hindering bean emergence. As a rule of thumb, there needs to be enough available moisture in the top one to two feet of soil to ensure good germination and adequate plant growth from planting through early to mid-July when the monsoon season usually starts in SW Colorado. Beans should be planted into moist soil but no more than four inches deep by using the proper equipment, such as shoe-type planters with press wheels to ensure good soil-seed contact and minimize soil evaporation.
One should maximize soil water infiltration, storage, and conservation during the non-crop season (example, from wheat harvest to bean planting) through proper soil and weed management. No-till and minimum tillage practices are one way to conserve moisture but they are uncommon in SW Colorado. Regardless of the tillage system used, it is essential to keep the soil weed free throughout the “fallow” period. This means controlling volunteer wheat (or another crop) and winter annuals with tillage and/or herbicide in the fall and keeping it weed free thereafter. The cost of chemical weed control may be too high for most dry bean growers in SW Colorado, given the low level of production (400 to 500 lb/acre on average). Further weed control can be achieved through cultivation during the vegetative growth period.
Adjusting bean planting pattern and density provides another means of optimizing water and/or weed management. In SW Colorado, most dryland farmers plant beans in 30 to 36-in rows at 18,000 to 24,000 seeds/acre. Manipulating planting density within this range may not impact bean yield much, but one should plant lighter in dry years to optimize water use.
When water is scarce, avoid planting beans in fields with high residual nitrogen such as is usually the case after alfalfa. Too much nitrogen will promote excessive vegetative growth early in the season, thus depleting soil water quickly. Dry beans obtain most of their water from the upper 2 feet of soil but will extract water from deeper soil layers (2 to 4 ft.) during periods of high evaporative demand.
If water is available for supplemental irrigation, it should be applied early in the season and during flowering to early pod fill. Starting the season with a full soil moisture profile by pre-irrigating is a good hedge against drought in SW Colorado given the precipitation pattern. Dry beans are very sensitive to water stress during flowering to early pod fill, thus one or more irrigations during this period will boost seed yield. Applying water late in the season or too much water is not recommended since it would delay maturity and promote diseases such as white mold.
Dry beans are a crop that is well adapted to the soil and climatic conditions of SW Colorado. It is also one that requires less water for optimum production (16 to 20 in. of consumptive use) than most other field crops grown in SW Colorado. With proper management, it can be grown in most years and provide a decent income, in combination with other farm enterprises.
