Managing crops and soil following drought
By Wilma Trujillo
Colorado Extension Southeast Area Agronomist
The current drought conditions have many similarities to the conditions during the Dust Bowl of the 1930s. While soil management practices are better today, high temperatures and water shortages this past year created crop losses and poor environmental conditions that echoed the Dust Bowl.
The 2012 drought is the combination of a dry fall and high temperatures early in the spring. With the hotter than average temperatures in March, many plants began emerging earlier than usual. This premature start used up the little soil moisture that was available, setting the stage for severe water shortages later in the summer. Even when rainfall might have been sufficient, evaporation and plant transpiration from the fields into the atmosphere were high due to the hot temperatures throughout the growing season.
Where crops failed or were damaged by drought, questions arise on how to manage similar conditions in the future. Variability associated with weather patterns makes crop management decisions difficult.
With all of the soil water having been used this year to ward off drought conditions, it would take above normal precipitation to recharge the soils and get them ready for another growing season. What if the precipitation doesn't come, are there management practices that will alleviate the conditions?
There are numerous options to manage soils, crops, animals, and water resources. Conversion to no-till combined with crop residue mulch and cover crops, is an important option. Under extreme conditions, crop losses were seen under no-till. A positive environmental aspect is that even a small amount of standing biomass produced with no-till will be an effective conservation practice in reducing wind erosion potential and preventing conditions that were seen in the 1930s Dust Bowl era. It is important that we prevent the negative effects of wind erosion with conservation practices. Crop residue with no-till will reduce the evaporation rate, capture snow, and store precipitation in the coming months.
Another strategy is to conserve water in the root zone, minimize losses by runoff and evaporation, and transform blue (fresh surface and groundwater) and grey (urban wastewater) waters into green water (fraction of rainfall that is stored in the soil).
Integrated nutrient management, a judicious combination of chemical fertilizers with organic amendments (compost, biosolids), is needed to enhance soil organic matter content and maximize crop water use efficiency. Ability of mineral soils to hold water increases with the increase in soil organic matter content. Thus, best management practices of land use and management should enhance soil and ecosystem resilience to drought and other abiotic and biotic stresses.
In addition, time of planting, seeding configuration and plant populations are appropriate agronomic considerations. Choice of crop species, depending on site-specific considerations, is important to enhance crop diversity, including complex crop rotations, and integration of crops with livestock. Vegetative barriers and terraces may enhance water storage, reduce the evapotranspirative stressor of wind, and minimize risks of wind erosion.
The drought has provided an opportunity to revisit agricultural systems of managing soils, crops, water, and animals. Are the current practices sustainable, especially under conditions of harsh, uncertain, and abruptly changing climate? To avoid another Dust Bowl of the 1930s, it is the time to rethink how we use the natural resources. The drought of 2012 reminds us that soil and water resources must never be taken for granted.
For more information on drought mitigation, contact your local Colorado State University Extension offices or visit www.ext.colostate.edu.