Abstract
Tree species and fertilization sources may affect the soil organic carbon (SOC) and fertility in agroforestry (AF) systems in temperate regions, but this remains unexplored. This study assesses the longitudinal trends in the SOC and major nutrients in a 17-year AF site established on an Ultisol in Fayetteville, AR. We evaluated how management and fertilization (mineral vs. organic) affect the soil’s physical and chemical properties using the tree species: red oak (Quercus rubra L.) and pecan Carya illinoinensis (Wangenh.) K. Koch. Long-term applications of poultry litter increased the soil pH, whereas the Mg and S concentrations decreased compared to the baseline levels (1999). Poultry litter increased the soil P concentration in 53% compared to the baseline levels and reduced the soil C:N ratio. After 17 years, increased Ca, SOC, and N concentrations were observed in the soils under the pecan stands that received poultry litter. Positive correlations occurred between the SOC and N (r = 0.96) as well as the Ca (r = 0.71) and P (r = 0.61) at a soil depth of 0–15 cm. Our findings demonstrated that the changes in SOC and fertility in the AF soils vary according to tree species and fertilization, mostly due to distinctive leaf litter and nutrient inputs. Organic matter accumulation increased the SOC retention and nutrient availability in the temperate AF systems.
Highlights
Accepted: 3 March 2022Agroforestry (AF) systems are widely recognized for their economic relevance and associated ecosystem services
The soil Ca at the 0–15 cm soil depth differed by year, the soil P was affected by tree species, and the soil C:N ratio was affected by fertilization
After 17 years, the soils under pecan that received poultry litter had increased Ca, soil organic carbon (SOC), and N concentrations compared to the inorganic control, indicating a legacy effect of poultry litter and suggesting a differential effect of tree species on the soil organic matter (SOM) accumulation and nutrient availability in soils
Summary
Accepted: 3 March 2022Agroforestry (AF) systems are widely recognized for their economic relevance and associated ecosystem services. Multiple benefits of AF include soil organic carbon (SOC). Sequestration [1–3], improved soil fertility [4] and soil structure [5], diversification of production, and biodiversity conservation [6,7]. In the face of climate change, AF systems have drawn attention as they represent an alternative that can enhance SOC sequestration and mitigate greenhouse gas (GHG) emissions relative to less complex, agricultural systems [8,9]. AF systems can promote more sustainable food production by improving food security while preventing land degradation [10]. A proper combination of tree species and fertility management can expand such benefits of the AF systems, in temperate AF systems, this remains largely unexplored. More diverse and complex plant communities in agroecosystems promote niche differentiation [11] and complementation and may increase efficient use of resources (e.g., light, water, and nutrients), leading to greater above- and below-ground biomass [12]
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