|Camp Jr, Carl|
Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 21, 2001
Publication Date: N/A
Interpretive Summary: When crops are grown without irrigation, loosening of compacted soils with tillage implements is often necessary so that roots can grow throughout the soil profile. With subsurface drip irrigation, water is placed near crop roots. It was not known whether soil loosening of compacted soils would improve plant growth and yield when crops were grown with subsurface drip irrigation. We found that for cotton, shallow tillage did not affect either early-season plant water status or early-season plant nutrient status. Similarly, shallow loosening of the soil with tillage implements did not improve lint yield or fiber quality. This suggests that no-tillage production systems may be possible for cotton grown with subsurface drip irrigation on compacted soils. These results are important to scientists and university extension personnel designing improved irrigated cotton production systems.
Technical Abstract: Subsurface drip irrigation and conservation tillage are tools for improving water management for cotton (Gossypium hirsutum L.). Previous research with cotton grown with no-tillage over subsurface drip laterals suggested excessive soil compaction near the soil surface limited root proliferation and may be a cause for reduced yield potential. A two-year experiment was conducted to determine the effect of three levels of soil loosening (no-tillage, shallow in-row tillage with a rigid shank, and shallow tillage with a stubble mulch plow to loosen the entire surface layer of soil) on early season physiological parameters and productivity. The subsurface drip irrigation system had been used for seven years before initiating this experiment and provided two lateral spacings (1 m and 2 m). Early-season cotton leaf gas exchange, leaf nutrient concentrations, yield, and fiber quality were measured. The tillage implements loosened the soil as they were expected to (as determined with a cone penetrometer), but level of soil loosening had almost no effect on leaf gas exchange and leaf nutrient status. Similarly, tillage and lateral spacing did not affect cotton yield and quality. Although yield levels were not impressively high (mean yield of 1215 kg/ha in 1998 and 700 kg/ha in 1999), they were typical for irrigated yields in this region during those years. The results suggest no-tillage production of cotton over drip laterals on the SE coastal plain is a viable option.