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Peanut (Arachis hypogaea L.) in the USA is generally seeded after several primary tillage operations that may include disking, chisel plowing, moldboard plowing, and bedding (conventional tillage systems). Concerns over erosion and production costs have increased interest in reduced tillage systems. Production in reduced tillage systems minimizes ability to incorporate fertilizers below the pegging zone, and residue on soil surface could impact movement of calcium sulfate (CaSO4) into the soil, reducing Ca availability to pegs. Research was conducted from 1997 through 1999 to compare peanut yield and gross economic value of virginia market type peanut planted in conventional and strip tillage systems. Preplant fertilizer did not affect response to tillage. Response did not differ among conventional tillage systems consisting of disk, disk and chisel, or disk and moldboard plow or among reduced tillage systems. Pod yield of peanut grown in the most effective conventional tillage system exceeded yield when peanut was strip‐tilled into stubble of the previous crop, strip‐tilled into a wheat (Triticum aestivum L.) cover crop, or strip‐tilled into beds prepared the previous fall without a cover crop. Tillage system and CaSO4 rate affected pod yield and gross value independently. Gross value increased when CaSO4 was applied regardless of tillage system. These data suggest that preplant fertilizer at relatively low, remedial rates does not affect peanut response to tillage systems. These data also suggest that tillage system does not have a major impact on peanut response to CaSO4. Collectively, these data indicate that the highest peanut yields occur in conventional tillage systems.

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Blocking is sometimes ineffective in accounting for a field's systematic, spatial variation. In such cases, trend analysis has been proposed as an alternative method. This procedure fits a polynomial regression function (surface model) to account for some of the systematic variability. Computer simulated data were used to test the statistical validity of trend analysis. Data simulation facilitated this evaluation, because the experimental conditions of treatment variation, systematic variation, and random variation could be computer generated within prescribed limits. The validity of the significance levels in trend analysis was evaluated. Also, trend analysis was compared to the randomized complete‐block analysis with regard to power of test and estimation of treatment effect. These studies show that with proper restrictions on choosing the surface model, trend analysis has true significance levels close to assumed levels. In addition, trend analysis was often superior to the randomized block analysis in power, and offered less biased estimates of treatment effects, especially when the pattern of systemic variation was complex and curvilinear.

High Al saturation is one of the limiting factors to intensive cropping of many soils in the Cerrado of Brazil. A field study on the effect of lime rate and depth of incorporation on growth of corn (Zea mays L.) was conducted on an Oxisol (Typic Haplustox) at Brasilia. Lime rates used were 0, 1, 2, 4, and 8 tons CaCO3/ha and depths of incorporation were 15 and 30 cm. Incorporation of 4 tons of CaCO3 to a depth of 30 cm reduced Al saturation from 72% to < 5% on a soil which initially had 1.1 meq Al/100 cm3. Concentrations of soil solution Al decreased to very low levels at pH 5.5.Grain yields of three successive corn crops were increased by liming. Incorporation of lime to a depth of 30 cm resulted in higher yields than incorporation to a depth of 15 cm. Application of MgSO4 to the acid soil increased yields above the nonlimed treatment.Yield responses to liming were due to improved Mg nutrition and neutralization of toxic Al. Root length was increased considerably in the 0‐ to 15‐cm depth and doubled in the 15‐ to 30‐cm depth when Al was neutralized by liming. Increased root development in the 15‐ to 30‐cm depth of the deep lime treatments resulted in greater water utilization from this depth and decreased the detrimental effects of moisture stress at tasseling on corn yields.