Soils with a long-term history of animal manure application exhibit higher residual effects of nitrogen (N) in soil and can affect the efficiency with which N will be used. This study aimed to evaluate how the immediate and residual effect of 16 applications of animal manure reflects on yields of black oat and corn rotation system, as well as N use efficiency. The study was carried out in no-tillage from 2004 to 2016 in Brazil. The treatments were pig [...] ABSTRACT Soils with a long-term history of animal manure application exhibit higher residual effects of nitrogen (N) in soil and can affect the efficiency with which N will be used. This study aimed to evaluate how the immediate and residual effect of 16 applications of animal manure reflects on yields of black oat and corn rotation system, as well as N use efficiency. The study was carried out in no-tillage from 2004 to 2016 in Brazil. The treatments were pig

This study aimed to evaluate Cu, Zn, and Mn fractions in vineyard soils in two important wine-growing regions in Latin America, which have soils with different soil organic matter (SOM) and clay contents. Soils were collected from vineyards aged 35, 37, and 39 years (Serra Gaúcha) and 13, 19, and 36 years (Campanha Gaúcha). In each region, soils were collected from a non-anthropized area, and in the oldest vineyards, the collection was conducted on and between the planting lines. The available and total Cu, Zn, and Mn contents were analyzed in addition to the chemical fractions. The ΔCu, ΔZn, and ΔMn were also calculated by subtracting the contents of each fraction of the vineyards from the reference areas. The use of fungicides promotes increased metal contents in vineyard soils. In soils with high SOM contents, Cu tended to increase in the organic fraction in surface and depth. In contrast, Zn increased in the residual fraction, and Mn increased in most bioavailable fractions. Cu and Zn increased their contents in soils with low SOM and clay contents in the organic and mineral fractions. Mn accumulated in the mineral and residual fractions.

Subtropical soils can have medium to high soil organic matter levels, which directly affects cation exchange capacity (CEC) and potassium (K) availability to plants. This generates the need to define K buffer capacity (KBC) values and K corrective rates to improve the fertilization recommendation system for these soils, ensuring high yields and reducing the likelihood of K losses in the environment. This study aimed to define KBC values and the K rates to be applied in corrective fertilization of acidic soils with high SOM and CEC _pH7.0 in a subtropical climate, and evaluate K corrective rates in vineyard soils in relation to the regional fertilization recommendation. Thirty-one native forest soils from the subtropical climate of Serra Gaúcha (RS), Southern Brazil, were collected. The samples were incubated with ten rates of K ₂ O for 30 days, with three replicates. After the incubation period, available K (K_M1) contents were obtained by the Mehlich-1 extractor. The K_M1 contents of the 0.00-0.20 m layer of 209 vineyards in the region were evaluated in the 2021/22 and 2022/23 crop seasons. Natural K_M1 contents in 97 % of the forest soils evaluated were classified as "high" and "very high" availability. Average KBC value obtained was 3.1 kg ha ^-1 K ₂ O, indicating the nutrient rate required to increase the K_M1 content by 1.0 mg dm ^-3 . Correction rates for the low and medium K availability classes were, respectively, 170 % higher and 78 % lower than the current regional fertilization recommendation for fruit trees. The K_M1 contents in 38 % of the vineyard soils in the study region were classified as "very high" availability, indicating the possibility of reducing the use of K fertilization. We recommend adjusting the K ₂ O rates based on KBC values, aiming to maintain K_M1 contents in the "high" availability class, reducing production costs and unnecessary K nutrient applications.