Pearl millet [Pennisetum gluucum (L.) R. Br.] is grown worldwide in areas affected by wind erosion, but no data on associated damage to millet are available. Laboratory wind tunnel experiments were conducted to determine the kind and extent of damage to millet caused by wind, sandblasting, and burial. In Exp. 1, millet was exposed for 15 min to wind (8, 11, or 14 m s-') or wind + sand (8.3, 25.0, or 41.7 g ,-I-I sand abrader flux) at 8 and/or 16 d after emergence (DAE). Viable leaf area, leaf net photosynthesis, and NO3 content were measured through 21 DAE and dry matter production through 57 DAE. In Exp. 2, millet was seeded as three single seeds or in tufts, exposed to 25 g m-I s-' sand flux for 15 min at the 1-, 2-, or 3-leaf stage, and then manually covered by 15 mm sand. Survival was monitored weekly; dry matter was determined 70 DAE. In Exp. 1, survival was uniformly 100%. Wind alone or low sand flux had no effect on viable leaf area. High sand flux decreased viable leaf area by 74% at 2 d after the 8-DAE exposure and 42% at 5 d after the 16-DAE exposure. Photosynthesis of the remaining leaf area was reduced up to 88% immediately after exposure compared with the control, and NO3 content of sandblasted millet was increased up to six times. Dry weight was reduced 40% at 21 DAE by the highest sand flux, but 9.7% at 57 DAE. In Exp. 2, burial decreased millet survival and dry weight. Buried tufts had a higher survival rate and 35% more dry weight than buried single plants. Millet buried at the 1-leaf stage had 28% higher survival than plants treated later. Sandblasting reduced dry matter of buried millet only. Regression analyses between calculated total kinetic effects and growth parameters showed low ? values. Millet can survive short-term sandblasting at any growth stage, but growth is reduced by strong sand flux, a sequence of wind erosion events during early growth, or by combinations of abrasion with burial by blown sand. s IND EROSION affects 430 million hectares worldwide, w o r 897 o of the susceptible dryland areas (UNEP, 1992).

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.

Wind erosion suspends large quantities of dust in the atmosphere that settle back to the earth's surface and are deposited on plant leaves when wind velocities decrease. The object of this research was to determine the effect of wind-erodible size dust particles on upland cotton (Gossypium hirsutum (L.) 'Dunn I20') growth and physiology.Dust ( < O.I06 mm) at concentrations of 0, I0.8, I5.2, I6.5, 22.I, 28.6, 38.5, and 5l.I l'g m-2 was settled onto leaves of 22-day-old growth-chamber-grown cotton plants in a dust chamber. Net photosynthesis, dark respiration, dust concentration, leaf area, and dry weight were measured I, 3, 7, and I4 days after dust was applied. Applied dust(> I5.2 l'g m-2 ) resulted in reduced dry weight at 3, 7, and I4 days after application, but dry weight accumulation was not reduced by increasing dust concentration after day 3. The dry weight reduction was due to reduced photosynthesis, I and 3 days after dust application, and increased dark respiration, I, 3, and 7 days after application when dust application rates exceeded 28.6 l'g m -2 • This study indicates that particulate deposits can alter cotton growth without physical damage to the plant and without toxic materials present in the dust. However, rapid removal of particulates by wind and rain and low natural deposition rates (1.5 l'g m-2 day-') indicate that dust deposits on leaves should not be a major problem in cotton production.

Federal legislation mandates that wind erosion soil losses be kept to a “tolerable” limit to maintain eligibility for federal farm programs on highly erodible land. Therefore, much interest has been generated in devising wind erosion models that accurately determine the potential erosion from a given site and also evaluate the effectiveness of any control measure. These models require mathematical relationships between surface properties and the transport capacity of the wind. Such relationships are available for soil surface roughness and plant residues, but not for growing crops. Our objective was to establish these relationships for growing crops. We developed a theoretical approach that accounts for the effect of stem area, leaf area, and canopy cover of growing crops on the soil loss ratio, threshold velocity, and transport capacity. The predictive ability of the theory was tested using published data sets from growing plants tested in a wind tunnel. Measured soil loss ratios were highly correlated to predicted values (r2 = 0.99, P = 0.001). The results showed that plant area index and canopy cover are highly correlated with reduction in the transport capacity of the wind and, therefore, serve as indicators of the soil protection afforded by growing plants. A plant area index of 0.02 and a canopy cover of 4% reduced the transport capacity of a 16 m s−1 wind by 50%. This method for determining the protective ability of a combination of growing plants and standing residue will improve predictive capabilities of wind erosion models for more diverse farm management conditions.

A climatic index based on effective precipitation and wind velocity for a 3‐year period ending May 31 can be used to predict with considerable certainty the severity of wind erosion conditions during the succeeding calendar year. On the basis of predicted severity of wind erosion conditions, farmers can be advised whether or not they should initiate special methods to control impending wind erosion.