A 5‐yr cropping system experiment was initiated in 1981 to study transition from a conventional agricultural system using pesticides and fertilizers to a low‐input system. The site was primarily Comly silt loam (fine‐loamy, mixed, mesic, Typic Fragiudalf) with 12% Berks shaly silt loam (loamy‐skeletal, mixed, mesic, Typic Dystrochrept), and a small area of Duffield silt loam (fine‐loamy, mixed, mesic, Ultic Hapludalf), in Berks County, eastern Pennsylvania. Three 5‐yr rotations were compared. A conventional corn (Zea mays L.)‐soybean [Glycine max (L.) Merr.] rotation (designated “conventional”) was compared to two low‐input rotations which utilized oat (Avena sativa L.), red clover (Trifolium pratense L.) and winter wheat (Triticum aestivum L.), in addition to corn and soybean. One low‐input rotation used cattle manure as a nutrient source and produced forage crops in addition to cash crops (designated “low‐input/livestock”), while the other used legume crops as a nutrient source, and produced a cash crop every year (designated “low‐input/cash grain”). Corn grain yields in the low‐input systems were 75% of conventional in 1981 to 1984, but yields were not significantly different in 1985. Weed competition and insufficient N limited low‐input corn yields during the first 4 yr. Soybean yields in the low‐input systems were equal to or greater than conventional all 5 yr. It is concluded that a favorable transition from input‐intensive cropping to low‐input systems is feasible, but only if crop rotations are used which include crops that demand less N and are competitive with weeds, such as small grain, soybean, or legume hay. Corn should be avoided for the first 3 to 4 yr.

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Soil physical and biological properties often change when different cropping, tillage, or management systems are imposed. Changes occasionally occur quickly, but usually become evident only after months or years. Infiltration rates are affected by several soil properties and may provide the most sensitive indication of changes in soil properties. To evaluate the use of infiltration measurements for detecting changes in soil properties, we conducted infiltration tests on a cropping systems experiment, a tillage experiment, and two beef cattle grazing experiments. In Pennsylvania, significant changes in infiltration rates did not occur until more than four years after converting from a conventional to a low-input cropping system. Infiltration rates were higher on 14th-year no-till plots compared with moldboard plow and chisel treatments in an Iowa tillage study. Earthworm populations and activity were highest in the no-till treatment. Infiltration rates correlated negatively with increased stocking rates in a long-term beef grazing study in Oklahoma. The number of earthworms did not correlate positively with infiltration in this study, suggesting a complex interaction. A short-term study of overwinter beef corn-stalk grazing in Iowa did not show consistent patterns in infiltration rate or other soil properties with different stocking rates. Infiltration appears to be a good indicator of soil structural changes associated with cropping, tillage, and management systems.

Soil temperatures in the northern Corn Belt are often too low at planting time to allow optimum germination, emergence, and early seedling growth. Crop residues, which are beneficial for erosion protection or are the result of minimum tillage, generally retard the rate of drying and warming of the seedbed. We found that ridged soils dried faster starting at the peak of the ridges and continuing down their southerly exposed slopes. Maximum seedbed temperatures occurred either under the ridge peak or under the southerly exposed slope. The time of the diurnal maximum temperatures depended on the slope aspect. For example, a southeast‐facing slope reached maximum temperature over 2 h earlier than a southwest‐facing slope, although the southwest slope reached a higher maximum temperature. Mulch decreased daytime soil temperatures, but a combination of mulch and ridging offset this temperature decrease so that there was no difference between a seedbed temperature under a mulch‐covered ridge and a conventionally tilled soil without mulch. Mulch with ridging provides a limited means of managing soil water and soil temperature in the seedbed.

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Tillage with a tined cultivator (scarifier) and a rotary cultivator was done on Urrbrae fine sandy loam in South Australia. One‐half of the plots were kept bare, while the other one‐half were cropped with wheat (Triticum aestivum L.). Soil macrostructure (voids and aggregates > 0.5 mm) was observed on sections sawed from blocks of the tilled soil which had been impregnated with epoxy resin. Macrostructure was quantified statistically along linear transects on the sections at 0.25, 0.5, and 0.75 of the depth of tillage at the time of tillage and on three subsequent dates when there had been 10, 135, and 395 mm of natural rainfall, respectively. Soil structures are compared and differences between them are presented. Initial differences in soil structure between the tillage treatments had largely disappeared by the second sampling date. Differences in structure due to the presence of the wheat crop were not significant until the final sampling date when the crop was at 0.66 of its final height. Multiple regression equations are presented for the soil macrostructure parameters as functions of cumulative rainfall after tillage and depth in the tilled soil layer.

Double rows of corn (Zea mays L.) spaced at regular intervals in a soybean (Glycine max (L.) Merr.) field served as temporary windbreaks at two locations in western Minnesota. In 1969 at Dumont, Minnesota, corn windbreaks were placed between every 14 rows of soybeans (every 11.4 meters), and in 1970 at Lamberton, Minnesota, 22 rows of soybeans (17.5 meters) separated the corn windbreaks. Moisture stress was high in 1969, but moisture was adequate in 1970.Small, white evaporimeters provided estimates of potential evaporation, soybean plant potometers furnished information on potential transpiration, and the stomatal resistances of the soybean leaves were measured by a porometer and from leaf impressions. Windspeed and potential evaporation were reduced significantly over the first seven or eight soybean rows on the lee side of the windbreaks. Potential transpiration and stomatal resistance varied significantly among rows between corn windbreaks and in some cases showed cyclic trends over rows. Potential transpiration and stomatal resistance appeared to be directly related when moisture stress was low, but were inversely related when moisture stress was high.Sheltered soybean yield increases and variations over rows were largely an accumulation of the variations that occurred in the plant‐water relations during the growing season.

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