Agrosystems, Geosciences & Environment最新文献

There has been a rapid increase in research to understand the genetic and agroclimatic interactions of hemp (Cannabis sativa L.) relative to its economic viability. Initial field trials at New Mexico State University were conducted in 2021 and 2022 at three sites across the state for high-cannabidiol (CBD), grain, and fiber hemp types. The goal of this work was preliminary evaluation of factors, such as variety choice and production conditions (specifically, water stress and organic management), to highlight topics that should be studied in full variety trials. Even with the limited scope, two important lessons from the studies are expected to be valuable for the developing industry: (a) the majority of available, compliant industrial (grain/fiber) varieties show severely shortened vegetative phases and early reproductive responses at low latitudes; and (b) high-CBD varieties perform inconsistently in outdoor production, rarely producing flower biomass yields and total CBD content necessary for economic viability. Future work is needed in the southwestern United States to find grain/fiber varieties with genetics suitable to the latitude and to reduce the costs of indoor production of CBD varieties.

Sorghum (Sorghum bicolor L. Moench) is an important and genetically variable food crop. In Hirna, eastern Ethiopia, 49 sorghum genotypes were evaluated for genetic diversity, heritability, genetic advance, and correlations throughout the main rainy seasons of 2017 and 2018. The experiment was arranged in a lattice square design with three replications. Information on traits relating to yield and phenology was collected. The analysis of variance revealed significant differences (p < 0.01) between the sorghum genotypes for each parameter in both experimental years. The phenotypic and genotypic variants for the cropping years 2017 and 2018 were 5.07%–26.36% and 7.10%–27.35%, respectively, and 6.70%–21.09% and 4.16%–21.30%. The highest estimates of heritability were linked to high genetic advance over mean for days of 50% blooming, leaf number, panicle length, 1000-seed weight, severity, and area under the disease progress curve in the 2 years. Over the course of the two trial years, correlation analysis showed a varied relationship between the qualities. Leaf width, leaf number, leaf length, leaf area, panicle length, panicle weight, and panicle width have shown a positive and significant correlation with grain yield. However, it exhibited strong and negative relationships with anthracnose disease parameters at the genotypic and phenotypic levels across the two growing seasons. The current experiment revealed high levels of genotypic and phenotypic diversity in Ethiopian sorghum genotypes, which raised the prospect of taking the variety into account for next development initiatives. Furthermore, the high heritability together with the high genetic advance observed in the studied characters indicated that selection based on these traits could be rewarding.

Industrial hemp (Cannabis sativa L.) has garnered increasing attention in the United States for its environmental and economic potential, yet its effects on mineral soil health remain largely unexplored. This study assessed the impact of hemp cultivation on soil quality by examining different hemp varieties and nitrogen (N) fertilization rates across three distinct subtropical agroecosystems in Florida. Over 2 years, field experiments were conducted at three University of Florida/Institute of Food and Agricultural Sciences research centers—West Florida Research and Education Center (Dothan fine sandy loam, pH 6.25), Plant Science Research and Education Unit (Arredondo sand, pH 6.25), and Tropical Research and Education Center (Krome gravelly loam, pH 8.4)—using a randomized block design. Three hemp varieties (IH-Williams, Wife, and Maverick) were cultivated under varying N application rates to evaluate their effects on soil organic matter (OM), nutrient levels (total and available N, and total phosphorus and potassium), and potential environmental benefits, such as reducing soil nitrate-N (NO₃⁻-N) losses in agricultural systems. Results indicated that hemp cultivation, particularly with high-cannabidiol varieties Wife and Maverick grown for flower production, significantly (p < 0.05) increased soil OM and influenced soil N dynamics. All hemp varieties significantly (p < 0.05) reduced NO₃⁻-N concentrations, while N fertilization had varying effects on total N and ammonium-N. Such findings will contribute to developing best management practices for optimizing nutrient applications and maximizing hemp's potential in improving soil health and promoting environmental sustainability across Florida's agricultural landscapes.

Efforts have focused on managing agricultural lands to optimize ecosystem health and provide key ecosystem services, including soil carbon (C) sequestration, yield stability, and climate resilience. These efforts often rely on adopting climate-smart practices, including no-till agriculture, crop diversification, cover cropping, and the application of compost and manure. However, there is limited understanding of the effects of long-term management on soil C sequestration and climate mitigation in row-crop production systems of the US Corn Belt. Using 20-year data (2001–2020) from the AmeriFlux and the Long-Term Agroecosystem Research network sites in Nebraska, we examined the total soil organic carbon (SOC) stocks and change under different management practices at two field-scale sites in eastern Nebraska. Both sites were under irrigation, but one site represented continuous maize (Zea mays L.; CM) and the other site represented maize and soybean [Glycine max (L.)] (MS) rotation throughout the study period. Evaluation of the changes in SOC stocks using direct soil measurements showed that long-term agricultural management had minimal effect on SOC stocks under irrigation, compared to the baseline (2001) level. Statistical analysis revealed no significant effect of management practices on SOC stocks (p < 0.05). In fact, the eddy covariance method shows a small SOC loss, although not significant (p < 0.05). Additionally, analysis of the SOC change using three methods showed large variation in SOC stocks between and within sites, indicating that sources of uncertainties associated with different methods need to be quantified for accurate assessment of SOC stocks at scales. Further analysis of the effects of crop rotation indicated that CM had the highest SOC stocks, compared to MS rotation. Our results show that despite two decades of conservation-tillage and no-tillage practices in highly productive CM and MS cropping systems, there were no significant changes in SOC. These differences were primarily driven by the direct feedback between rates of biomass production, post-harvest residue retention, biological activity, and SOC formation and stabilization.

Members of the Solanaceae family, such as tomatoes (Solanum lycopersicum), eggplants (Solanum melongena L.), and peppers (Capsicum chinense L.), are moderately sensitive to salinity, which could limit their production, especially under future water limitations and decreasing irrigation water quality. Heirloom cultivars provide valuable genetic resources for enhancing salinity resilience, yet their potential for intrinsic tolerance in Solanaceae crops remains unexplored. In this study, we built on earlier research by comparing relatively salt-sensitive and salt-tolerant cultivars of tomato, eggplant, and pepper under multiple salinity treatments using both chloride- and sulfate-dominant irrigation waters. For each cultivar, we measured yield, biomass, ion concentrations, and gene expression profiles to gain insights into the mechanisms underlying salinity tolerance. The results indicate that these Solanaceae varieties may have higher salinity tolerance than reported in the literature (e.g., Food and Agriculture Organization Irrigation and Drainage Paper 61), with a notable increase in the yield reduction threshold for the sulfate treatments and potentially lower slope as assessed with the Maas–Hoffman model. Gene expression results revealed that salt-tolerant cultivars in eggplant, tomato, and pepper (e.g., ‘Long Purple’, ‘Red Pear’, and ‘Ancho’) showed consistently more effective regulation of key Na⁺- and Cl⁻-transport genes than their salt-sensitive counterparts (e.g., ‘Black Beauty’, ‘Jaune Flamme’, and ‘Corbaci’). This included enhanced ion extrusion at the root surface, improved vacuolar sequestration of ions within cells, and tighter control over root-to-shoot ion movement. Together, these traits promoted tissue-level tolerance by maintaining ionic homeostasis and preventing excessive ion accumulation. These results suggest that heirloom varieties are a potential genetic source for future plant breeding efforts to improve salinity tolerance in the “solanaceous” species studied.

Deep placement of phosphorus (P) fertilizer significantly increases crop yield and nutrient uptake in rainfed cropping systems. However, genotypic differences in root system architecture (RSA) play an important role in response to P rates and placement strategies. This study investigated genetic variation in RSA and its effect on exploiting deep P bands in four contrasting, early- to late-maturing mungbean (Vigna radiata L.) varieties. Four P treatments were control (no additional P), surface (30 mg P mixed in the top 5 cm), sub-layer (30 mg P mixed at 20- to 25-cm depth), and deep band (30 mg P applied in a band at 20-cm depth). The randomized complete block design included four replications. RSA was measured in the top and bottom 30 cm of the soil profile. Shallower P placement widened root growth angle by 14%, while deeper placements increased mean root diameter and root volume by 15% and 31%, respectively. Deep banding and sub-layer treatments advanced flowering and increased pod yield in the early-maturing variety Berken, without significantly altering root surface area, P uptake, or shoot P concentration. Berken also showed the lowest shoot P concentrations, least P uptake, and greatest internal P use efficiency. Genotypic differences in RSA and root functioning played a major role in response to P placement, with the strongest response observed in the deep P band treatment, despite a lack of root proliferation. These findings provide insights into optimizing P placement and selecting mungbean genotypes for improved productivity in rainfed cropping systems.

Crop production is threatened by low soil fertility and soil acidity in high rainfall areas, while escalating lime and fertilizer costs call for alternative local materials. In this regard, the ameliorative effects of termite-mediated soils (TMS) as a liming material and source of essential plant nutrients should be investigated. Therefore, 2-month soil incubation and pot trials were performed to evaluate TMS effects on soil acidity properties as well as growth and yield of barley (Hordeum vulgare) in comparison to lime-amended and control soils under greenhouse conditions. Surface soil samples to 30-cm depth were collected from an acid-prone area for the setting up of the trial, while TMS was analyzed for lime and nutrient content before application. The experiments were laid out in a completely randomized design with four and three replications for the incubation and pot trials, respectively. Results showed that TMS had an overall effective neutralizing power of 62.7% and fineness index of 89.6%. This reveals TMS raised soil pH as effectively as pure lime in both the incubation and pot trials. The combined application of lime materials at 75% improved soil pH immediately, while the supply at 100% resulted in an immediate pH improvement in the incubation trials, and the effects are long-lasting. The combined application at 100% improved the chemical properties of soil as well as the growth, yield, and yield components of barley in a pot trial. In conclusion, TMS had the potential to condition soil acidity while supplying essential nutrients. However, further study underlying the acid ameliorative effects of TMS under field conditions is necessary to fully understand its benefits, particularly for early crop establishment.

In the Northern Great Plains, the period between small grain harvest and the first killing frost leaves soil vulnerable to erosion, particularly if crop residue is removed or reduced by tillage. Integrating cover crops can reduce erosion risk and improve soil health, but in water-limited areas, overwintering cover crops may lower soil water content and delay spring germination. This eastern North Dakota study evaluated how crop residues and cover crops influence soil temperature and water content. Three treatments were tested after barley (Hordeum vulgare L.): (1) bare soil, (2) barley residue, and (3) cereal rye (Secale cereale L.) and flax (Linum usitatissimum L.) cover crops no-till drilled into barley residue, producing 224 kg ha⁻¹ of aboveground spring biomass. Soil temperature, water content, net radiation (R_n), and soil heat flux (G) were measured from April 18 to May 23, 2023. Surface cover significantly affected R_n, G, and temperature compared to bare soil. Bare soil had the greatest cumulative R_n and G, which increased soil temperatures at the 3-cm depth (9.3°C) compared to barley residue (7.9°C) and cover crops (7.6°C). Although bare soil had higher mean temperatures, it had the lowest minimum temperature during cooling periods. Despite expectations that cover crops would reduce soil water, no significant differences were observed.

Hemp (Cannabis sativa L.) was re-legalized as an agricultural crop through the USDA 2018 Farm Bill, but cropping guidelines remain limited, especially for floral hemp grown for cannabinoid extraction. In this study, the response of direct-seeded, field-grown autoflower and full-season hemp cultivars to varying rates of applied irrigation was compared over multiple years in a semi-arid environment. Measurements included floral and total biomass, cannabinoid concentration, and cannabinoid yield. The primary flower size did not vary much regardless of irrigation amount, even for plants grown with no supplemental irrigation. As irrigation increased from very low levels up to 100% of the location's potential evapotranspiration (PEt) and beyond, leaf and stem biomass continued to increase as the plants also got taller. Secondary and tertiary flower biomass increased with irrigation, but only up to about 80% of PEt. Above that amount, floral biomass typically plateaued for both autoflower and full-season types. Floral cannabinoid concentrations did not vary much regardless of irrigation amount. Irrigating at rates greater than about 80% of PEt does not generally increase cannabinoid yield. In contrast, under very dry conditions hemp can grow, reach maturity, and produce some flowers and associated cannabinoid yield even when receiving little or no rainfall or irrigation. Thus, growing hemp with low, moderate, or no irrigation in a semi-arid climate may be economically feasible (despite the lower yield) in certain situations, depending on costs of irrigation water, other crop management decisions, and market valuation of end products.

Management practices that increase soil organic carbon (SOC) and nitrogen (N) stocks improve soil health, crop productivity, and agricultural sustainability. Irrigation is crucial in mitigating the effect of sporadic droughts on agricultural productivity in the southeastern Coastal Plains of the United States and is well-recognized for improving SOC and N accrual under semiarid conditions. However, our understanding of its impact on SOC and N storage in sandy soils under humid climates is limited. Our objective was to quantify the differences in SOC and N storage between irrigated and rainfed management in a humid agroecosystem. We sampled four typical southeastern Coastal Plains soils in the United States: Bonneau (BnA), Dunbar (Dn), Norfolk (NkA), and Noboco (NcA), all of which are loamy sand, both in irrigated and rainfed areas of the same experimental field. We found no significant difference in soil respiration (as 3day-CO₂-C), microbial biomass carbon (MBC), hot water-extractable carbon (HWEC), inorganic N, and labile organic nitrogen (LON) between irrigated and rainfed conditions. In addition, we found no difference in SOC and N stocks under the irrigated versus rainfed scenario. Our results indicated that 29 years of supplemental irrigation had no significant impact on soil C and N fractions or SOC and N storage compared to rainfed conditions under continuous long-term conservation tillage.