21 Our Advertisers Appreciate Your Business Better Farming | January 2025 “Pore size distribution in the soil – which refers to the relative amount of small versus large pores or holes in soil – affects the ability of soil to hold water against gravity,” says Schoenau. “This is affected by the minerals and organic matter and how they are stuck together. When we think about soil with good soil structure, it has mineral particles cemented together by organic matter to form larger aggregates. This creates a distribution of pores ranging from small micropores, which are effective at retaining water against gravity, to larger macropores that are necessary for drainage to occur and allow the exchange of gases between the soil and external atmosphere.” Ammeter adds, “Soil has the ability to hold water on soil particles and organic matter, but also in pores spaces. The soil texture will also determine the size of pore spaces. Clay has many small holes that hold lots of water, whereas sandy soils have fewer large holes which hold less water.” Producers looking to improve capacity can manage their soils to increase organic matter. They can also pay more attention to improving water infiltration and reducing evaporation. Improving it The clay, silt, and sand content of a soil, termed soil texture, cannot be significantly influenced by management. Instead, farmers can best manage their soil to increase organic matter, which has many benefits in addition to improving water holding capacity. Soil organic matter can also support soil fertility, biology, and structure, improve infiltration of water, and reduce erosion. “Organic matter is critically important. Any practice that will negatively impact soil organic matter will also negatively impact soil water-holding capacity,” says Ammeter. “To improve water-holding capacity, do the opposite. Use practices which will increase organic matter, including reduced tillage, maintaining crop residue on fields, and avoiding baling or burning crop residue.” She notes that soil erosion can be particularly damaging to soil water-holding capacity, as the topsoil is typically highest in organic matter. Schoenau, whose research focuses largely on soil fertility and chemistry, says that his lab has also found that some crops will utilize water from different depths depending on their rooting habit. He recommends rotating these crops to use available soil water in the soil profile more efficiently. “The kind of crops you grow, particularly in a rotation, can affect soil water use efficiency,” says Schoenau. “In recent research, we looked at cereals in rotation with pulses, specifically wheat and peas. We noticed that wheat tends to take water from a deeper depth, and peas tend to use water from shallower depths. Over the course of a rotation, we saw improvement in water use efficiency and INCREASING WATER-HOLDING CAPACITY 22_0470_MH_Agricultural_HalfHoriz_US_MXsp Mod: December 2, 2024 4:17 PM Print: 12/02/24 page 1 v2.5 TAKE YOUR PICK HUGE SELECTION ALWAYS IN STOCK ORDER BY 6 PM FOR SAME DAY SHIPPING πSHIPPING SUPPLY SPECIALISTS COMPLETE CATALOG 1-800-295-5510 uline.ca
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