Soil Profile Gravel Layers: II. Effect on Growth and Water Use by a Hybrid Forage Sorghum1
- Paul W. Unger2
A hybrid forage sorghum (Sorghum vulgare Pers. × Sorghum vulgare var. sudanense) was planted in field plots having a gravel layer placed on or 5, 15, or 25 cm below the surface, and in check plots. Rapid soil drying delayed seedling emergence about 2 days for the 5-cm treatment in 1969, and for all except the surface gravel treatment in 1970. In both years, rainfall several days after seeding resulted in good seedling emergence and plant establishment. However, the delayed emergence retarded early growth, and plants were tallest at harvest on the surface gravel plots. Dry-matter yields of the first crop were highest on the surface gravel plots, but second-crop (plant regrowth) yields were highest on the check plots each year. Nitrogen deficiency may have reduced yields for the second crop on the surface gravel plots in 1969. Also, the second crop was uniformly irrigated each year, which resulted in more uniform soil water replenishment than that occurring from rainfall. Subsequent water use by the crop was similar on all plots. The subsurface gravel layers interfered with deep-infiltration of water from rainfall and reduced the utilization of rainfall for crop production on these plots. Trends in water use efficiencies were similar to trends in dry matter production.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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