Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 1997
Publication Date: November 1, 1998
Citation: Wilhelm, W.W. 1998. Dry-matter partitioning and leaf area of winter wheat grown in a long-term fallow tillage comparisons in the u.s. central plains. Soil & Tillage Research 49:49-56. Interpretive Summary: Crop development and growth are linked to the environment to which the crop plant is exposed. In non-irrigated agriculture, fertilization, tillage, and residue-management practices are the main ways in which producers modify the soil environment to enhance crop production. In this long-term study of the influence of fallow tillage practice and N fertilization, modification of the soil environment by these practices had an influence on wheat root development and distribution patterns. A greater mass of root tissue was produced at anthesis with the no-till treatment than with the plow or sub-till treatments, but at other sampling times in both years of the root studies (1978 and 1979) tillage treatments did not change root masses. Averaged over tillage and N treatment and years, about 510 lb/ac of root tissue was present at mid grain fill. This is about 7% of the above ground dry matter production. On average, 50% of the total root tissue was in the upper foot of soil and at least 80% of the root tissue was in the top 2 feet of soil. During 1979, less dry matter was produced by late grain fill with addition of N fertilizer (8300 lb/ac) than when N was not applied (8500 lb/ac). In contrast during 1980 (at about the same stage of development), application of N resulted in more above ground dry matter production in the plow and no-till treatments, but addition of N reduced production in the sub-till treatment. Grain yield followed similar trends. Nitrogen application increased tiller production and number of tillers surviving to maturity.
Technical Abstract: Interpretive Summary: Crop management practices (tillage, residue management, fertilization, etc.) define the soil environment to which crops are exposed and through these environmental conditions control crop growth. The purpose of this paper is to report the response of winter wheat (Triticum aestivum L.) to long-term (10 years) application of fallow tillage practices (plow, sub-till, and no- till) and N fertilization in terms of above and below ground dry matter partitioning. During 1978, less winter wheat root tissue was produced in the sub-till treatment compared to the average of the plow and no-till treatments. However, in 1979 all treatments produced the same amount of root tissue. Averaged over all treatments, root tissue was about 7% of the above ground dry matter production. During 1979, less above ground dry matter was produced at late grain fill (27 June) with addition of N fertilizer (929 g/m2) than when N was not applied (957 g/m2). In contrast during 1980 (at about the same stage of development), application of N resulted in more above ground dry matter production in the plow and no-till treatments, but addition of N reduced production in the sub-till treatment. Grain yield followed similar trends. Nitrogen application also increased tiller production and number of tillers surviving to maturity. Nitrate reductase activity was measured to determine if the reported lesser levels of nitrate-N in soils under reduced tillage management changed N metabolism of the plant.