Wind erosion produces textural changes on topsoil of semiarid and arid environments; however, the selection of particles on different textured soils is unclear. Our objectives were to evaluate textural changes induced by wind erosion on cultivated soils of different granulometry and to asses if textural changes produced by wind erosion are linked to aggregation of granulometric particles into different sizes of aggregates formed in contrasting textured soils. Considering this, we studied the particle size distribution (PSD) with full dispersion (PSD F ) of 14 cultivated (CULT) and uncultivated (UNCULT) paired soils and, on selected sites, the PSD with minimum dispersion (PSD MIN ) and the quotient PSD MIN/F . Results showed that the content of silt plus clay was lower in CULT than in UNCULT in most of the sites. The highest removal of silt was produced in soils with low sand and high silt content; meanwhile, the highest removal of clay was observed in soils with medium sand content. According to PSD MIN , particles of 250-2,000 μm predominated in the sandy soil, in the loamy soil particles between 50 and 250 μm and in the silty loam soil particles between 2 and 50 μm. For clay sized particles, PSD MIN/F was lower than 1 in all soils and managements, but this quotient was higher in CULT compared with UNCULT only in the loamy soil. This means a decrease of clay accumulation in aggregates of larger sizes produced by agriculture, which indicates an increase in the risk of removal of these particles by wind in loamy soils.

No abstract

No abstract

Core Ideas DTPA‐extractable Zn is often used to predict corn response to Zn application. Can DTPA–Zn‐based diagnosis be improved by considering other soil properties? Soil properties did not contribute to explain corn grain yield response. DTPA–Zn allowed to discriminate sites based on their response to Zn fertilization. We determined a Zn‐critical range from 0.86 to 1.30 mg kg−1 (n = 64). Current zinc (Zn) diagnostic methods for corn (Zea mays L.) are often based on soil DTPA (diethylenetriamine‐pentaacetic acid) extractable Zn (DTPA‐Zn). However, calibration of the DTPA‐Zn test may be influenced by other soil properties such as pH, organic matter (SOM) and available Bray‐P (PBray‐1). Our objective was to assess the contribution of soil properties to a DTPA‐Zn model used to predict corn response to Zn fertilization. We conducted 64 field trials with two Zn‐fertilization treatments: with and without Zn fertilization. In all sites, we measured SOM, PBray‐1, pH, and DTPA‐Zn at 0‐ to 20‐cm depth before sowing. Yield difference between Zn‐fertilized and unfertilized treatments (Ydifference) was significant in 33% of the experimental site‐years. In responsive site‐years, the average Ydifference was 0.98 Mg ha‐1 (11.4%). Soil organic matter was the only property that was a significant addition to the DTPA‐Zn model for predicting the corn relative yield (Model R2 including SOM = 0.27). However, the improvement was nominal (Partial R2 of SOM = 0.06). Use of DTPA‐Zn alone was suitable to discriminate Zn responsiveness among site‐years based on the Ydifference by correctly diagnosing 81% of the outcomes. We determined three soil DPTA‐Zn ranges with different probability of resulting in a Ydifference greater than zero when fertilized with Zn: high (<0.9 mg kg‐1), medium (0.9–1.3 mg kg‐1), and low (>1.3 mg kg‐1). These soil‐test‐based Zn recommendations improve the identification of Zn‐deficient soils allowing prevention of yield loss from Zn deficiency and more rational use of Zn fertilizers.

No abstract