Abstract:
Climate remains the most significant anthropogenic phenomena, destabilizing agriculture, forests, and human livelihoods. Prolonged use of chemical-based conventional agriculture has elevated Green House Gas (GHG) emissions and reduced Soil Organic Matter (SOM) due to low residue turnover, lack of soil cover, and frequent tillage. Although agriculture has the potential to function as a carbon sink through soil and biomass, it has become a notable source of GHG emissions. Implementing cover crop-based alley cropping with high-value vegetable crops in orchards of fruit, nut, or timber trees offers a promising strategy to enhance land productivity and reduce the carbon footprint by lowering GHG emissions and increasing carbon storage in both soil and biomass. This approach can be further strengthened by adopting reduced- or no-till practices and off-season cover cropping in the alleys, which help minimize erosion and enrich SOM through root exudates and litter incorporation. Alley cropping improves land-use efficiency, biodiversity, and carbon and nitrogen sequestration, while also reducing GHG emissions and providing consistent cash flow. This system is well-suited for enhancing climate resilience and food security. To evaluate these benefits, an alley cropping study was conducted using specialty crops (two Solanum varieties, two Capsicum varieties, and two leafy vegetables) among newly established loblolly pine and pecan nut stands under an organic production system. A mixture of grain rye (Secale cereale) and red clover (Trifolium pratense) served as a fall cover crop. Measurements included soil respiration, carbon sequestration, and saturated soil hydraulic conductivity (Ksat) between trees and in vegetable crop plots, in addition to vegetable crop yields. Results indicated that soil respiration rate, total nitrogen, and total carbon were higher in the loblolly pine system compared to the pecan system. The highest total carbon sequestered was observed for Chinese eggplant at 1.8% and 1.9% in the pine and pecan nut systems, respectively. Average Ksat values were 3,575 and 4,928 cm d-1 in the vegetable crop beds of the pine and pecan systems, respectively. In the pecan system, average Ksat ranked as follows: Indian eggplant>sorrel>lemon basil>sweet peppers>Chinese eggplant>ancho peppers. In the loblolly pine system, the ranking was: lemon basil>sweet peppers>ancho peppers>Indian eggplant>sorrel>Chinese eggplant. Indian eggplant produced average fresh fruit yields of 11,428 and 13,357 kg/ha in loblolly and pecan nut tree stands, respectively, exceeding those of Chinese eggplant by more than 120%. Fresh fruit yields from capsicum averaged 3,236 and 2,974 kg/ha in loblolly pine and pecan stands, respectively. Sorrel and basil yields ranged from 6,027 to 17,289 kg/ha. Building on the success of this system, a subsequent approach incorporated high-yielding, high-value fruit trees such as persimmons (Diospyros kaki), blueberries (Vaccinium virgatum), and figs (Ficus carica) intercropped with specialty vegetable crops including ginger, turmeric, eggplants, colored bell peppers, pumpkins, and sorrel (Hibiscus sabdariffa). The study demonstrated that specialty vegetable crops provide continuous cash flow from July through November, ensure economic returns and food security, and enhance carbon sequestration, nitrogen accumulation, and soil hydraulic conductivity.
Keywords: Agroforestry, Alley Cropping, Climate Change Mitigation.