Drylands cover 40% of the global surface and house more than 2 billion people. Drought-tolerant crops are becoming more important in these regions, not only to provide food, fodder, and energy, but also to sequester soil organic carbon. This study evaluated soil and root system attributes of forage cactus ‘Orelha de Elefante Mexicana’ (Opuntia stricta Haw.) managed using different agronomic practices in the Brazilian Semiarid. The experiment was established in June 2011 and the design was split-plot in a randomized complete blocks, where the main plot was the different planting density, and the subplots were the factorial arrangement between harvest frequency and harvest intensity. Soil samples were collected at 0 to 10 and 10 to 20 cm depths and response variables included root biomass, soil bulk density (BD), and soil carbon (C) and nitrogen (N) contents and stocks. Sampling occurred in August 2019, but for root biomass and soil BD analysis it also occurred in September 2021. There were no significant effects from management practices on root biomass at 0 to 10 and 10 to 20 cm depth (p > 0.05), with respective averages of 12.45 Mg ha⁻¹ and 6.06 Mg ha⁻¹. Soil BD was similar at 10 to 20 cm depth (p > 0.05) averaging 1.28 g cm⁻³. Soil organic carbon (SOC) stock varied with management and reached almost 100 Mg C ha⁻¹ in the 0 to 20 cm layer, indicating the potential of cactus to store carbon. Plants with a more developed root system are more likely to survive the drought climatic condition; therefore, less dense plantings could result in more resilient plants for drier regions, but could potentially negatively affect biomass productivity per area.

The use of silvopastoral systems with tree legumes is a viable alternative to recover and develop pastures, as they add N to the system influencing pasture growth. This study hypothesized that the herbage and litter of signalgrass (Urochloa decumbens Stapf) is affected by legume trees in the pasture. Treatments were composed of (1) signalgrass + Mimosa caesalpiniifolia Benth.; (2) signalgrass + Gliricidia sepium Jacq.; and (3) signalgrass monoculture. The 3-year experiment followed a randomized complete block design with three replications. Tree legumes were planted in double rows (15 × 1 × 0.5 m), in 1 ha paddocks. Litter samples were taken in five distance points (0, 1.8, 3.7, 5.6 and 7.5 m) perpendicular to tree legume rows. Signalgrass was taller at longer distances from the trees (P < 0.05). Signalgrass height differed between treatments, with taller signalgrass found in pastures mixed with G. sepium (15.6 cm) compared to M. caesalpiniifolia (9 cm) (P < 0.05). Herbage N content decreased with increasing distance from tree rows (P < 0.05). Litter N content followed a similar pattern, ranging from 23 g/kg under the trees to 12 g/kg at 7.5 m away from tree rows. Signalgrass did not grow under the tree crown (0–1.8 m), especially when intercropped with M. caesalpiniifolia. The findings of this study suggest that the type of legume trees used in the silvopastoral system has the potential to modify the pattern of grass growth and content of N in pasture litter.

Management practices might alter soil chemical properties. This study evaluated soil chemical properties in a forage cactus Opuntia stricta (Haw.) Haw. (‘Orelha de Elefante Mexicana’) (OEM) production system in the Brazilian semiarid region. The experiment was established in June 2011, and the design was a split-split-plot in randomized complete blocks, in which the main plots were formed by distinct levels of organic fertilizer (cattle manure) (0, 10, 20, and 30 Mg ha⁻¹ year⁻¹), the subplots were formed by different levels of N inorganic fertilizer applied as urea (0, 120, 240, and 360 kg N ha⁻¹ year⁻¹), and the sub-subplots were distinguished by the distinct OEM harvesting frequency (annual or biennial). Soil samples were collected for chemical analysis, C and N contents analysis, and stocks analysis at 0 to 10 and 10 to 20 cm depths in August 2019. Organic fertilizer contributed to a linear increase in soil pH, Ca²⁺, Na⁺, sum of bases (SB), cation exchange capacity (CEC), and base saturation (V) at both depths (p < 0.05). With the application of 30 Mg ha⁻¹ year⁻¹ of cattle manure, there was storage of approximately 126 Mg C ha⁻¹ and 13 Mg N ha⁻¹ at 0 to 20 cm depths. Managing OEM with organic fertilizer and a biennial frequency of harvesting affects the soil’s chemical characteristics in cactus orchards, and it is a sustainable alternative for semiarid regions.