Growth analysis methods are useful tools for describing plant response to environmental variations (Rad- ford, 1967; Hunt, 1982). The objective of this study was (NT) often appear smaller than those grown with conventional tillage to test our hypothesis that a combination of compensa-(CT), yet they produce similar grain yield. Our objective was to test the hypothesis that the early-season growth depression is offset by tory growth and changes in plant development are recompensatory growth and changes in plant development. A 2-yr field sponsible for stable grain yield in the face of reduced study was conducted at Urbana, IL, on a long-term tillage experiment. early-season plant growth for soybean on a high organic Grain yield, moisture, protein, and oil content were similar for CT matter, well-structured soil in the central Corn Belt. and NT treatments. Total plant, stem, leaf, and pod dry biomass were all initially about 15 to 20% greater under CT, but the difference MATERIALS AND METHODS declined until about R5 or R6; thus, compensatory growth did occur. At the initiation of sampling (V2) crop growth rate was about 20% Field Procedures greater under CT, but the difference declined until about R2. The Field studies were conducted during the summers of 1993 advantage shifted to NT until about R6. Leaf area index (LAI) was and 1994 at the Agricultural Engineering Research Farm of greater for CT until about R4. Net assimilation rate was greater for the University of Illinois at Urbana-Champaign. This study NT until about R5. Increases in early-season crop growth rate for CT was superimposed on a long-term tillage experiment in a corn was due to increased LAI. Greater crop growth rate for NT late in [(Zea mays (L.)]-soybean rotation that was established in 1986 the season was due to increased net assimilation rate. Leaf weight on a Thorp silt loam field (fine-silty, mixed, mesic Argiaquic ratio was larger for the CT crop until about R6. Specific leaf area Soybean [Glycine max (L.) Merrill] plants grown with no-tillageArgialbolls) with 3.1% organic matter and a pH of 6.7. From was less in CT than NT. This work supports our hypothesis that the six tillage systems included in the long-term tillage expericompensatory growth and alterations in plant development occur ment, we selected two for this study: conventional tillage and when soybean is grown in NT systems and helps to explain why grain no-tillage. The CT consists of fall moldboard plowing (20-25 yield does not decrease with NT even though early-season growth cm deep) of corn residue followed by spring disking (7.5-10 is affected.cm deep) and field cultivating in preparation for soybean. The NT, by definition, has no tillage or cultivation. The experiment design is a complete randomized block with four replications,

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Corn (Zea mays L.) production problems of uneven growth, yellowing, and reduced yields have been reported by producers on fields where agronomically acceptable rates of liquid beef manure were spring injected. Field experiments were conducted from 1983 through 1986 in northwestern Illinois on a Derinda silt loam (fine, mixed, mesic Typic Hapludalf) soil to determine the effect of method of liquid beef manure application and manure placement relative to the corn row on plant and grain N concentration and grain yield. Placement studies showed that corn plants growing over knife‐injection zones had the highest N concentration and greatest yield. Corn offset at parallel distances of 10, 20, and 30 in. from the injection zone had decreased N concentrations and lower yield than corn planted over the zone. In 1986, the year with the largest yield decline, corn 30 in. from the injection zone yielded 56 bu/acre less than corn planted over the zone. This positional relationship and limited availability of manure N appear to be the major factors related to yield decreases associated with knife injection. Yield reduction with sweep injection or broadcast application occurred in 1986, but was attributed to volatile N loss because of improper injection‐incorporation. Nitrification inhibitors increased some whole‐plant, ear‐leaf, and grain N concentrations but did not significantly increase grain yield. Supplemental inorganic N increased grain yield when volatile loss of manure N occurred. Sweep injection, with more uniform manure distribution appears to be a practical alternative to knife injection.