Research monitoring N uptake by various agricultural crops has shown total N accumulations in the plant to increase prior to the growth stages around heading to flowering with a subsequent decrease in total N occurring after flowering. Volatilization of N from the plant may account for much of this loss as well as account for some of the deficits exhibited in N balance studies. Experiments were conducted in a gas‐tight growth chamber to determine what role plants alone may play in the overall loss of N from the soil‐plant system. Winter wheat (Triticum aestivum L.) was established, vernalized, and grown to maturity in the growth chamber. At first internode elongation, the chamber was closed and sealed for the duration of the experiment. Air supplied to the chamber during this period was bubbled through 1 N H2SO4 to remove ambient NH3 and through a reagent specific to NO and NO2 to remove these gases. Air samples were continuously drawn from the chamber and bubbled through 0.2 N H2SO4 to trap evolved NH3. These samples were collected weekly and analyzed using steam distillation. A second portion of the air sample was washed through the NO‐NO2 specific reagent and analyzed colorimetrically. Only trace amounts of NO and NO2 could be found at any time during the experiment leading to the conclusion that volatilization of these gases does not contribute significantly to the loss of N from the plant. Ammonia volatilized from the system at the rate of 0.34 to 0.89 ✕ 10−1 mg NH3‐N/m2/day prior to flowering. After flowering the rate of NH3‐N evolution increased to 1.03 to 1.32 ✕ 10−1 mg/m2/day. This dramatic increase in the rate of NH3‐N evolution at flowering coincides with the plant growth stage that researchers have begun to observe deficits in total N accumulations in the above ground portion of the plants. This data supports the hypothesis forwarded here, that volatilization of NH3 from plant tissue can partially account for the deficits in total N accumulation observed in plant tissue following flowering.

Alternate methods of residue management for reduced tillage under irrigation and in double cropping systems are constantly being sought. One method that is becoming increasingly popular is residue burning. Knowing how to best manage crop residues to maintain desirable soil physical properties for decreasing erosion and increasing crop yields in these cropping systems is a problem. This study was conducted to determining the influence of several methods of residue management for winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] on physical properties of Richfield silty clay loam (fine, montmorillonitic, mesic Aridic Argiustolls). Residue management treatments were: residue removed by burning, residue removed by baling and hauling, incorporation of the residue produced during the immediate past cropping season, and incorporation of twice the amount of residue produced by the crop. Most of the soil physical properties measured were not influenced by either grain sorghum or wheat residue management treatments; however, they differed between crops. The soil aggregates from the sorghum plots were smaller, more fragile, less dense, less stable dry, and more stable wet than the aggregates from the wheat plots. The pore size distribution of the soil from the Ap horizon of the sorghum plots was more conducive to water infiltration. The saturated hydraulic conductivity was several times greater in the soil cores obtained from the sorghum plots than those obtained fro the wheat plots.

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Phosphate fertilizer recommendations for winter wheat have traditionally been in terms of doubling the row applied P rate if broadcast application is to be used. A literature search failed to locate a significant amount of supportive data for this practice. The experiments reported here were conducted to determine if there is a consistent relationship between broadcast and row applied P rates for winter wheat and if so, what that relationship is. Six field experiments were conducted over a 2 year period on soils of, the Typic Argiustoll subgroup. Treatments were five rates of 0‐46‐0 (0, 11, 22, 34, 45 kg P/ha) applied as either preplant broadcast or drilled with the seed. All experiments were on soils that responded positively to P fertilization. Results contradicted the concept of a 2:1 ratio of broadcast to row P application as standard practice. The relative effectiveness of row and broadcast methods changed with changing soil tat P levels. Low soil test locations exhibited an effective ratio of about 3:1 while medium soils tests had ratios of 1:1.