|Evett, Steven - Steve|
Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/1997
Publication Date: N/A
Interpretive Summary: The earth's soil serves to anchor plants and provide them food and water, but not all soils are alike. They differ in how much water they can hold, in what their parent materials are, and in how they developed, all of which may affect how well the plants grow. We studied the growth and yield of grain sorghum, a common agricultural crop in our area, in three contrasting gsoils that are found in the southern Great Plains region. The soils were clay loam, which holds a lot of water but has a layer of calcium type material layer beginning about four feet down; a silt loam, which is a very uniform soil throughout and holds a lot water; and a sandy loam, which also has a calcium type layer and does not hold much water. We compared how the crops grew when they were well-watered and under limited water, or water stressed. We found that even when the plants in the sandy loam were well watered, they did not grow well or produce as much grain as the crops on the other two soils, possibly because the plants could not root as well in the dense sandy soil. They water in the silt loam drained slowly, keeping the soil unusually wet. The crop in that soil did not grow well when the soil was well watered, perhaps because there was not enough oxygen for the plant roots to use for a brief period of time, but did grow and yield better compared with the other two soils when it was water stressed. The crop in the clay loam produced good grain yields, but would not use the water in the calcium layer until it had depleted most of what was available in the upper layers. We found that soil type does affect how well a plant grows.
Technical Abstract: Soil type and the climate in which it occurs control crop growth and yield. We conducted a study to determine the influence of contrasting soil types on grain sorghum (Sorghum bicolor Moench) growth, water use, and yield. In 1992 and 1993, grain sorghum ('DK-46') was grown in 0.75-m rows with 16 plants m**-2 at Bushland, TX, in lysimeters containing monolithic soil cores of silty clay loam, silt loam, and fine sandy loam. The 1992 irrigation treatments were well-watered (WW) and no applied early season irrigation to achieve a pre-anthesis water stress. The 1993 irrigation treatments were WW with limited irrigation during late vegetative and reproductive growth stages to achieve a post-anthesis water stress. The crop in the silt loam soil produced lower grain yield in 1993 under high soil water conditions, but higher grain yield, total biomass, and seed number under limited irrigation compared with the crop on the clay loam. The crop in the sandy loam consistently produced the lowest leaf areas and yield components in all irrigation treatments, possibly due to high soil bulk densities which may have restricted rooting. Water use was typically highest in all treatments in the silt loam, which extracted water uniformly throughout the profile. The presence of a strong calcic horizon in the clay loam and sandy loam delayed crop water use in that horizon, and possibly limited some water use through restricted rooting. Soil type affected both water use and yield of grain sorghum.