Agroforestry systems have the potential to increase soil organic matter, with effects on soil carbon and nitrogen contents, but information on the application of these systems in semi-arid regions is still scarce. This study aimed to analyze soil carbon and nitrogen stocks in the conversion of native forest from the Caatinga Biome into integrated agriculture systems in the Brazilian semi-arid region. We evaluated the following management systems in the Haplic Inceptisol (Cambissolo Háplico eutrófico): (1) Intercropping area, cultivated with [...] ABSTRACT Agroforestry systems have the potential to increase soil organic matter, with effects on soil carbon and nitrogen contents, but information on the application of these systems in semi-arid regions is still scarce. This study aimed to analyze soil carbon and nitrogen stocks in the conversion of native forest from the Caatinga Biome into integrated agriculture systems in the Brazilian semi-arid region. We evaluated the following management systems in the Haplic Inceptisol (Cambissolo Háplico eutrófico): (1) Intercropping area, cultivated with

The objective of this work was to propose preliminary Diagnosis and Recommendation Integrated System (DRIS) norms and derive critical levels and nutrient sufficiency ranges in the leaves of guava plants in commercial nursery conditions. Sixty-eight leaf samples were evaluated from fertilization trials with seedlings. In the low-yield subpopulation (84% of the population), the limiting nutrients by deficiency in descending order were nitrogen (N)> copper (Cu)>phosphorus (P) = potassium (K)> manganese (Mn)> iron (Fe) = zinc (Zn)> sulfur (S)> boron (B) = magnesium (Mg)> calcium (Ca), and the limiting ones by excess in descending order were B > Ca > Fe > Mn > S > Mg > Cu > P > Zn > N = K. The ranges of the appropriate DRIS indices were 24 to 28, 2.4 to 3.1, 21 to 29, 6 to 8, 1.9 to 2.9 and 1.9 to 2.3 (g kg⁻¹) for the macronutrients N, P, K, Ca, Mg and S, respectively, and 35 to 48, 4 to 15, 68 to 93, 31 to 60 and 180 to 245 (mg kg⁻¹) for the micronutrients B, Cu, Fe, Mn and Zn, respectively. The dry matter production of guava seedlings was associated with the nutritional status.

Establishing sufficiency ranges and critical levels of nutrients are important for a correct evaluation of plant nutrition through leaf diagnosis. This study aimed to propose critical levels and sufficiency ranges of macro and micronutrients based on leaf diagnosis of soybean plants. The database used was generated from 86 samples of the third trifoliate leaf without petiole, collected during the flowering stage from soybean plants of the main cultivars used in the states of Piauí and Maranhão, Northeast region of [...] ABSTRACT Establishing sufficiency ranges and critical levels of nutrients are important for a correct evaluation of plant nutrition through leaf diagnosis. This study aimed to propose critical levels and sufficiency ranges of macro and micronutrients based on leaf diagnosis of soybean plants. The database used was generated from 86 samples of the third trifoliate leaf without petiole, collected during the flowering stage from soybean plants of the main cultivars used in the states of Piauí and Maranhão, Northeast region of

The conversion from native forest to other land-use systems can decline the soil organic carbon (SOC) in tropical soils. However, conservationist management could mitigate SOC losses, promoting the functioning and stability of agricultural soils. This study aimed to address the influence of conversion from native forest to different land-use systems on SOC fractions in Northeastern Brazil. Topsoil soil samples were collected in areas under pasture (PAS), no-tillage (NT1 and NT2), eucalyptus (EUC), and native forests of Cerrado in Northeastern, Brazil. Total organic C, microbial biomass (MBC), particulate (POC), and mineral-occluded organic C (MOC), as well as fulvic acids (C-FA), humic acids (C-HA), and humin (C-HUM) fractions were accessed. The results showed that land conversion maintained similar levels of humic fractions and total organic carbon (TOC) stocks in the PAS, NT1, NT2, and EUC as compared to native Cerrado. Soils with the input of permanent and diverse fresh organic material, such as NT2, PAS, and EUC, presented high levels of MBC and POC, and the lowest C-FA:TOC and C-HA:TOC ratios. The land conversion to agricultural systems that include cropping rotations associated with pasture species such as Mombasa grass and eucalyptus prevents topsoil losses of active C compartments in the Cerrado of the Brazilian Northeast. It suggests that sustainable and conservationist management should be emphasized to maintain and improve the status of soil organic C.

The present study aimed to compare the use of leaf and flower analysis and to verify the most appropriate organ for the diagnosis of the nutritional status of guava trees. The evaluation was carried out using the CND (Compositional Nutrient Diagnosis) methodology, using yield and nutritional contents of the leaf and flower of ‘Paluma’ guava trees in 48 plots of an irrigated orchard. The contents of flower and leaf nutrients were submitted to variance analysis, by the Tukey test at 5%, and the nutrient sufficiency ranges in organs were calculated, as well as the correlations between multi-nutrient variables and yield. Significant differences between contents of nutrients in flower and leaf, as well as greater variability in the nutritional contents in leaf, were observed. The sufficiency ranges of flower proved to be shorter compared to leaf. The number of correlations between nutrients and yield was higher in the flower. The greater sensitivity of the leaf analysis in expressing interactions between nutrients and yield indicates that this organ can also be used for the nutritional diagnosis of guava trees.