Soil health: Building a resilient landscape
Tuesday, October 22, 2013 3:54 AM
Summer and fall 2012: drought. Spring 2013: record rainfalls and wet conditions prevent planting. Fall 2013: drought with intermittent downpours.
The weather extremes over this past year leave us all puzzled about how to maintain crop production and protect our natural resources. A big part of the answer could be soil health. Droughts and floods are perceived to be controlled by the amount of rainfall, but the quality of the soil can have a huge effect on how the landscape reacts to periods of drought or flooding. Healthy soils absorb water better and hold water in the root zone longer for plants to use during dry periods.
Soil health improves as organic matter increases. Organic matter is added by crop residue, living plant roots, manure, compost and mulch. The microorganisms that live in the soil convert these things to organic matter, and in the process release a substance called glomulin that holds soil particles together like glue and gives it structure. Good soil structure makes the soil less prone to erosion and more able to absorb and hold water. In effect, good soil health has a buffering effect during times of extreme weather, making the land more resilient to unfavorable conditions and more productive. The microorganisms that live in the soil also help plants take up nutrients and water from the soil.
The USDA has developed four simple principles for soil health. More information is in the "Soil Biology Primer" at www.soils.usda.gov/sqi/concepts/soil_biology/biology.html.
1) Keep the soil covered with growing plants and/or their residues to conserve moisture and protect the soil from the force of falling raindrops; soil aggregates that remain intact at the soil surface help water to infiltrate to the plants' roots. A crop residue mulch also suppresses weeds and keeps the soil cool and moist - a favorable habitat for soil organisms.
2) Minimize soil disturbance. Tillage compacts the soil and leaves it bare and vulnerable to erosion. Misuse of fertilizers or pesticides disturbs the soil chemically and biologically. Both these scenarios create a hostile environment for soil organisms.
3) Diversify with crop diversity, and the soil organisms will also be diverse, creating a variety of food and energy chains and webs that utilize as many different sources of food as possible in the soil.
4) Continual live plants grow living roots throughout the year, and the root zone is the most active part of the soil factory. Roots feed the soil organisms responsible for breaking down crop residues and cycling the nutrients in the soil so they are available to the plants. When living roots are absent, the process is much slower.
Time-tested practices that improve soil health are minimum till and no till; cover crops; crop rotations that include hay, small grains and other high residue crops; rotational grazing; hay and grass contour strips and buffers; and efficient nutrient and pest management. Integrating livestock into farming operations helps to recycle nutrients and build organic matter through the use of manure. Livestock also utilize pasture and hay and other forages, which enrich and protect the soil.
The Fillmore Soil and Water Conservation District Board of Supervisors consists of: Travis Willford, Harmony; Brian Hazel, Lanesboro; Pamela Mensink, Preston; Tim Gossman, Chatfield; and Leonard Leutink Jr., Spring Valley.