In the last blog, a pictorial of high quality soil, we showed some pictures showing the difference in poor soil quality and good soil quality and its effect on water infiltration.
After 1 day of sun the ponding decreased, however an additional 0.5” resulted in ponding again, the garden did not pond.
Poor infiltration leads to in-season water stress. Water stress limits the development of young plants and reduces grain fill and development fruiting plants. Water stress also raises leaf temperature, which increases the likelihood of severe spider mite infestations.
Slow water intake reduces irrigation efficiency since a greater portion of the water applied is lost to evaporation. Finally, slow water intake increases the potential for compaction since planting and harvesting are often performed before the soil is sufficiently dry.
Slow water intake can result in prolonged standing water, which reduces the needed oxygen required for proper soil health. Standing water can cause N loss by waterlogging soil bacteria. The bacteria starving for oxygen, will scavenge oxygen from soil nitrate. As a side effect, these scavenging bacteria break down the nitrate molecules, causing de-nitrification.
The Common causes of poor infiltration are:
1. Compaction of surface soil from traffic.
2. High sodium content (Na) causes soil particles to be forced apart chemically (called deflocculation). This can result in surface sealing by reducing pore size.
3. Inadequate salt content of the surface soil is just as big a factor in slow infiltration as high content. Irrigating with low salt water (less than 250ppm) or excessive rainfall, which is very low in salt content eventually, leaches enough salts from the surface soil to reduce its structure. This creates smaller pore spaces, which have higher surface tension, and less permeability.
4. Subsurface soils with distinctly different texture are often overlooked as a water related problem. It does not cause slow infiltration at the soil surface; rather it limits downward movement of water into the lower root zone. Soils of different texture vary greatly in the number and size of air spaces through which water travels. When downward moving water encounters a zone of different soil texture, it must overcome the surface tension created by the different pore size. Saturated soil conditions occur above the layer until sufficient pressure (head) builds up to overcome this.
The Blogronomist is maintained by Craig Dick, head blogronomist and VP of Sales and Marketing. Here you will find a wide array of blog articles from Craig and expert guests on topics related to soil and crop health, farming, and so much more. If it’s not here, ask us!