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- Author or Editor: E. D. Threadgill x
Abstract
The disk, deep turn and rip-bed methods of land preparation resulted in soil strengths of 1000 kPa or greater at depths of 10, 28 and 18 cm, respectively. The disk and deep turn treatments produced a relatively uniform soil strength across the seed bed at all depths while the rip-bed treatment resulted in a channel of low strength soil under the row with relatively high soil strengths 15 cm to each side. Root growth generally followed the same pattern as soil strength. Shelled pea yield was greatest with the deep turn tillage method and lowest with the disk tillage method. The greater yield was due to a combination of a larger yield per plant and a slightly greater plant stand with the deep turn tillage method. Nutrient use efficiency as determined by total nutrient uptake by plants of the rip-bed and deep turn treatments was 40 and 50% greater than those from the disk treatment.
Abstract
‘Dixie’ squash (Cucurbita pepo L. var. condensa) were subjected to factorial combinations of 2 irrigation levels, 4 N treatments, and 3 tillage methods on a Lakeland sand soil during 1978, 1979, and 1980. The greatest marketable fruit yield resulted from a combination of applying irrigation at 0.3 bar soil water tension, applying 22.5 kg N/ha through the irrigation system at 2, 3, 4, 5, and 6 weeks after planting, and preparing the seedbed by moldboard plow tillage. Yields were reduced 3 to 16% by either reducing the N rate, allowing a greater soil water tension before irrigating, or by the use of subsoil-bed or disk-harrow tillage system. A combination of subsoil-bed tillage and application of irrigation at 0.6 bar soil water tension resulted in the greatest yield when squash received a single N application after planting.
Abstract
Response of sweet corn (Zea mays L.) to tillage methods on a Tifton loamy sand was investigated during 1976 and 1977. The greatest volume of soil having a strength of less than 100 N/cm2 core index resulted from moldboard plowing to a depth of 28-30 cm. The smallest volume of low-strength soil resulted from disk harrowing to a depth of 10-13 cm. Soil strength patterns produced by these tillage methods were relatively uniform across the seedbed. A subsoil-bed system produced a channel of low-strength soil under the row to a depth of 40 cm; however, soil strengths 15 cm to the side of the row were similar to the disk harrow method. Soil strength patterns resulting from subsoil-plant systems were similar to subsoil-bed. Soil strength increased during the growing seasons with tillage differences evident near harvest. Root growth, plant growth, yield, and nutrient uptake efficiency responses of sweet corn were proportional to the volumes of low-strength soil at planting.
Abstract
Activated charcoal was applied as a spot treatment on soil surface over the seed of watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai, cv. Charleston Gray]. Planting and charcoal application were done simultaneously with specially developed equipment. Activated charcoal at 358 kg/ha fully protected watermelon from terbacil (1.12 kg/ha) injury but provided only partial protection from atrazine (2.24 kg/ha) injury. Spot application of activated charcoal did not result in decreased weed control.
Abstract
Disc tillage of turnip greens (Brassica campestris L. Rapifera group) caused an abrupt increase in soil strength below tillage depth, which in turn prevented turnip root penetration. Soil strength of 85 N/cm2 on Lakeland sand and 100 N/cm2 on Tifton sandy loam prevented penetration of turnip roots. In general, root fresh and dry weights were unaffected by tillage treatments. Turnip root growth with the disc treatment was shallow, whereas turnips grown with subsoil-bed and subsoil-plant tillages developed deeper root systems. Balanced downward and horizontal turnip root systems were developed with mold-board plow preplant tillage.
Abstract
Preplant tillage treatments influenced growth and yield of turnip greens (Brassica campestris L. Rapifera group). Yields in response to moldboard plow, subsoil-bed and subsoil-plant treatments were not significantly different on either Tifton sandy loam or Lakeland sand. Yields with the above tillage treatments were significantly greater than with disc treatments on Lakeland sand. However, on Tifton sandy loam, only moldboard plow treatment resulted in higher yields than with disc treatments. Plants with higher top fresh and dry weights were obtained with moldboard plow treatment on Tifton sandy loam but not on Lakeland sand. Disc treatment increased soil strength and decreased root length.