Mid-South soils - and soils in other areas - are becoming more depleted in sulfur. This is due, in part, because air pollution standards have lowered sulfur emissions and reduced acid rain. Less acid rain falls because many coal-fired utilities have installed modern scrubbers that remove the sulfur from emissions. Crops such as cotton, soybeans, corn and alfalfa will grow best with optimum sulfur. Read more
Intensive farming practices and acid subsoils have left a layer of toxic aluminum salts in many Mid-South soils. The toxic aluminum barrier inhibits root growth and water and nutrient uptake to a shallow zone just below the soil’s surface. This causes stunted, contorted tap roots and suppresses plant yields. Read more
Mid-South soils, especially those with high in silt and clay and low in organic matter, are prone to crusting and sealing at the surface following rainfall events. This is because clay particles in soil are easily dispersible or splattered across the soil surface as rainwater pellets the ground. When the water eventually recedes back into the soil, the clay is filtered onto the surface and forms a hard crust.
Crusted soils restrict many things. It is difficult for seedlings to emerge from in the early spring when soils are crusted over at the surface. Sealing also traps water just below the surface, like liquid is trapped inside a drinking straw as you hold your thumb over the top. The trapped water won’t evaporate so soils can’t “breath” or move oxygen. That’s detrimental to germination and growth and can lead to denitrification.
Highly productive soils soak up rainwater quickly and move moisture down through the soil profile so it is available when the crop needs it. Unfortunately, many Mid-South soils are slow to absorb water and ineffective in storing moisture. In heavy rains, the water runs off or fields may become ponded. This delays field work. When the fields are dry, the soil becomes hard and concrete-like. Because water doesn’t absorb well into the soil, the crop may suffer in drought conditions because it doesn’t have access to moisture deep in the soil profile. Read more
When soil is hard, tight and impermeable heavy rain runs off or water pools on the surface of the field. Wet spots are slow to dry which delays fieldwork and can cause poor root development, nutrient leaching and denitrification.
Denitrification occurs when soils are very wet and moisture drowns the soil pores, allowing very little room for oxygen to percolate. Soil microbes need oxygen. If depleted, the microbes will use the oxygen portion of nitrite and nitrate forms of nitrogen fertilizer. When this happens, nitrogen gasses are formed and evaporated into the atmosphere. The result is a loss of soil nitrogen the plant can access. This results in yellow or browned-out corn and can lead to significant yield losses because adequate nitrogen is essential for grain fill. Read more
Soil erosion by water - the loss of soil and sediment - is a serious problem that can have significant negative impacts on agricultural productivity, drainage and surface water quality. Eroded topsoil transfers into streams and other waterways, causing potential surface water quality problems and hydrological damage that can be far-reaching within a watershed. Topsoil losses also reduce agronomic productivity. Read more
Like soil and sediment losses caused by erosion, dispersible soils are prone to nutrient losses through runoff and surface water or tile output. This can cause nonpoint source pollution in watersheds if not corrected. Read more
Compacted soils limit root growth, cause drainage problems and impact nutrient availability. Some soil experts have likened compaction to pushing a load of bricks on the soil’s lungs. Compaction suffocates the soil’s ability to distribute water, air and nutrients.
Compaction is a result of equipment traffic and also an indicator of soil health. Soil compaction, referred to by soil scientists as soil density, can be determined using a penetrometer or by difficulty or ease in pulling equipment such as a planter or tillage tool.
1 "Soil-Building Tips for Better No-Till Productivity," Special No-Till Management Report No. 32, No-Till Farmer, July 2011, various articles.
Healthy soils should be alive with biological activity, promoting a vibrant habitat for soil organisms to decompose organic compounds such as plant residue, manure and pesticides. The soil organisms fix nitrogen, stabilize nutrients, enhance soil aggregation and porosity and feed on crop pests. In healthy soils, growers see soil test levels of organic matter climb and faster residue breakdown. Healthy soils also attract earthworms that break down residue and burrow into the profile to create air and moisture channels that plant roots can utilize. If soil is compacted and tight, growers may see fewer earthworms. Read more