Agrosystems, Geosciences & Environment最新文献

This study examines the impact of climate change on bread wheat (Triticum aestivum L.) yield in Central Oromia, Ethiopia, using climate and yield data from the past 32 years. Historical daily climate data were obtained from the Ethiopian Meteorological Institute, while observed wheat yield data were collected from the respective Zonal Agricultural Offices. Correlation analysis was used to assess climate–yield relationships, and simulated yield data were generated using multiple regression analysis to estimate yield responses to climate change. Trend and variability analyses were applied to evaluate climate patterns and their effects on wheat production. Results show significant increases in maximum temperatures at all stations, while minimum temperatures increased at 37.5%–75% of the stations. Annual rainfall increased at 37.5% of stations and decreased at 12.5%. Rainfall variability showed high concentration and irregular distribution, with annual precipitation concentration index values of 16%–20% and seasonal values exceeding 20%. Drought conditions, based on the Rainfall Anomaly Index, occurred in 72% of the years, classified as 22% extreme, 34% severe, and 44% moderate drought. The growing season started between 153 and 210 day of year (DOY) and ended at 275–282 DOY, lasting 101–120 days with 69–103 rainy days. Dry spell lengths during the growing season were below 5%, declined to nearly zero at peak season, and sharply increased in September, reaching 90%–100% by month's end across all stations. Climatic factors explained 43%–85% of wheat yield variability, although non-climatic factors also contributed. Overall, findings emphasize climate variability impacts on wheat production and the need for adaptive strategies and further research.

Enzyme activity studies provide an indicator of soil health related to soil management practices. As land area seeded to corn (Zea mays L.) and corn yields increase in this region, demands for plant nutrients also increase to support the high yields. Phosphorus (P) is the second highest fertilizer input in corn production representing a significant input cost. Phosphatase enzymes are produced by soil microorganisms and plants and aid in the release plant available P from soil organic matter when fertilizer P is limited. This is among the first acid phosphatase (ACP) activity studies of long-term (36 years) corn rotations with contrasting fertility regimes in the Northern Great Plains. Relationships between ACP and tillage type, nitrogen rate, and manure application under limited P fertilizer applications was evaluated in two long-term (36 years) corn rotations in east-central North Dakota. Acid phosphatase activity was determined on soil samples from the corn root zone from two crop rotations representing common crop mixes grown locally. Phosphatase measurement in contrasting tillage (clean-till vs. no-till), nitrogen (N) rates (0 and 168 kg ha⁻¹), and manure (with or without) applications showed that tillage and N rate did not significantly affect enzymatic activity. Manure applications significantly reduced ACP activity by 38%–50% indicating P accumulation suppressing enzyme activity, suggesting trade-offs of practices with soil health. Phosphatase activity was negatively affected by soil pH and soil test P (p ≤ 0.001) but not affected by soil organic matter and appeared to be within levels found in the literature due to maintenance of soil test P at medium levels.

This study examines the impact of soil erosion on corn (Zea mays L.) yield across counties in the US Midwest. Using a novel county-level panel dataset that includes information on water erosion and corn yield, we analyze the direct and spatial spillover effects of erosion using a spatial regression framework. We find that increases in soil erosion have a statistically significant negative impact on corn yield. In addition, we find evidence of significant spatial spillover effects, indicating that erosion in one county can adversely affect agricultural productivity in surrounding areas. These findings confirm that the negative effects of soil erosion extend beyond the site of origin and are spatially diffused across regions. This study provides new empirical evidence on the broader yield-related consequences of soil erosion and highlights the importance of landscape-level conservation strategies to mitigate its long-term agricultural impacts.

Soil health (SH) management has been promoted to improve climate resilience across agricultural systems. An on-farm field study was conducted to (1) evaluate the soil water storage (SWS) in SH and conventional (CV) management systems across four paired sites in Minnesota and Wisconsin and (2) to assess the response of these management systems to drought and significant rainfall (>25 mm in 24 h), using SWS as a primary metric. Two solar-powered soil probes with multiple capacitance sensors were installed from July to October in 2021 and May to October in 2022 and 2023 to monitor soil moisture every 30 min at 10-, 20-, 40-, 60-, 80-, and 100-cm depths. Daily average SWS at the root zone (0- to 40-cm depth) was significantly higher (p < 0.0001) under SH management compared to CV management. Out of the four sites, three showed at least 7% greater SWS in SH management compared to CV management. During extreme drought periods, the SH management sites consistently had at least 13% higher SWS, showing potential for improved soil moisture retention and resilience to drought. Our analysis showed the SH system captured 35% more water than the CV system overall, but inconsistencies across the sites highlight the need for a larger dataset and more in-depth analysis to better understand these patterns. Overall, the study indicates that SH systems with varying use of no-till, cover cropping, and organic amendments can improve the soil's ability to store more water during the growing season, enhancing the resilience of US Midwest agricultural fields.

In recent years, the escalating application of nitrogen fertilizers in global vegetable production has positioned vegetable fields as significant sources of nitrous oxide (N₂O) emissions, eliciting widespread environmental concern. However, the interrelationships among fertilizer reduction gradients, soil physicochemical properties, microbial biomass nitrogen (MBN), enzyme activities, N₂O emissions, and yield in highland summer cauliflower (Brassica oleracea var. botrytis L.) systems remain inadequately elucidated. This study, conducted in Yuzhong County, Lanzhou City, Gansu Province, employed the “Green Stalk 100-day” cauliflower variety under three fertilization regimes: CK (conventional fertilization), F1 (20% fertilizer reduction), and F2 (40% fertilizer reduction). The impacts of these treatments on soil properties, MBN, enzyme activities, N₂O emissions, and yield were systematically evaluated. Results demonstrated that compared with conventional fertilization, both F1 and F2 significantly reduced soil organic carbon, nitrate nitrogen (NO₃⁻), ammonium nitrogen (NH₄⁺), total phosphorus, and MBN. Cumulative N₂O fluxes under F1 and F2 decreased by 30.01% and 63.35%, respectively, relative to CK, with a pronounced declining trend as the growing season progressed. Both greenhouse gas balance (GHG) and greenhouse gas intensity (GHGI) were markedly reduced under reduced fertilization regimes. Additionally, under the F2 treatment, the biomass and yield of cauliflower exhibited significant reductions of 17.41% and 25%, respectively, relative to the control (CK). In contrast, F1 achieved substantial mitigation of N₂O flux, GHG, and GHGI without compromising yield stability. In conclusion, the F1 treatment represents the optimal strategy for balancing economic and environmental benefits in highland summer cauliflower production systems in the Yuzhong region of Gansu Province.

The historic development of the Post Oak Savanna ecoregion in Texas, USA, was shaped by natural wildfires. However, wildfire suppression has caused an increase in encroaching woody species. To address this issue, land management strategies incorporate prescribed fire (PF) for the control of encroaching species. Wildfire has been shown to impact soil physical and hydraulic properties as well as soil enzymatic activities; however, the effects of PFs, which are typically less intense than wildfires, are not as well-described. This study sought to quantify the effects, if any, of PF on soil physical and hydraulic properties and enzymatic activities in the Post Oak Savanna ecoregion. Comparative analysis was conducted on soil samples from 0 to 5 cm and 5 to 10 cm measured prior to and immediately after PF. Soil wet aggregate stability, unsaturated and saturated hydraulic conductivities, water retention, organic carbon, and enzyme activities were quantified. Results indicate that neither soil properties nor enzymatic activities were significantly altered due to low-intensity PF. Low-intensity PF has no immediate effect on soil physical and chemical properties or soil enzyme activity. Low-intensity PF is an effective land management tool that has no impact on the soil properties measured here.

Accurate mapping of rapeseed (Brassica napus) fields is critical for effective crop management, pollinator support, and yield forecasting. This study systematically evaluated the performance of 23 vegetation indices (VIs) for rapeseed detection during the peak flowering stage using high-resolution Sentinel-2A imagery across two contrasting agricultural regions: North Dakota and Spain. Each VI was assessed within a threshold-based binary classification framework. The normalized difference yellowness index (NDYI) consistently emerged as the most effective index in both study areas, achieving the highest classification performance in North Dakota (overall accuracy = 0.97, F1 score = 0.95, Kappa = 0.93, and producer's accuracy = 0.94) and in Spain (overall accuracy = 0.96, F1 score = 0.64, Kappa = 0.62, and producer's accuracy = 0.51). Other indices, notably green leaf index and CI, also showed relatively strong performance, while traditional greenness-based indices such as normalized difference vegetation index, soil-adjusted vegetation index, and modified soil-adjusted vegetation index achieved only moderate accuracy. Several color-sensitive indices clearly outperformed conventional metrics in distinguishing rapeseed from spectrally similar summer crops, whereas indices such as modified yellow index and high-resolution flowering index exhibited poor classification results in both regions. The optimal NDYI thresholds—0.69 in North Dakota and 0.60 in Spain—were closely aligned, indicating minimal regional variability and underscoring the robustness and transferability of NDYI for rapeseed mapping. Overall, these findings provide practical guidance for selecting suitable VIs and highlight the importance of spectral yellowness for accurate crop classification during the flowering stage.

In recent years, the invasive algae Rugulopteryx okamurae has spread along the Mediterranean and Atlantic coasts, causing ecological and economic damage. However, upwelling algae could provide a valuable source of carbon biomass for circular economy applications. Marine algae, particularly brown algae, have a long history of use in agriculture as biostimulants and biofertilizers, demonstrating their effectiveness on various crops and underscoring their potential as a valuable resource for sustainable agricultural practices. This study aimed to evaluate the agronomic effects of aqueous extracts from R. okamurae on radish growth using a rapid, cost-effective method, with the goal of exploring potential applications for upwelling biomass. Two groups of seaweed were used: one washed with distilled water and the other unwashed. Both groups were macerated in water for 10 days, with and without a mixture of activators (chickpea flour, poultry manure, brown sugar, and fertile soil). Four liquid extracts, along with a water control, were tested on Raphanus sativus. The results showed a significantly higher biostimulant effect on germination index and plant growth (root and shoot length, fresh and dry weight) compared to the control. The greatest increase in shoot and root length was obtained with non-washed seaweed (NWS), with improvements of +40.6% and +68.2%, respectively. The best performance in fresh and dry plant weight was achieved with non-washed seaweed + activators (NWS + A), which increased root fresh weight by +160.9% and root dry weight by +146.2%. These findings highlight the potential agronomic use of low-cost aqueous extracts from R. okamurae as biostimulants.

The development of an image-based method for determining soil water retention curves (WRCs) is effective for predicting infiltration processes into soil. We investigated the effects of microscopy magnification on image resolution for estimating WRCs. Images of the soil surface were acquired at magnification of 50×, 100×, and 200×. Large-sized pores (>30 µm in radius) captured at lower magnifications of 50× and 100× were closer to values obtained from the conventional method, pressure plate method, because images at low magnification could capture wide areas and measure representative values. The image-based method at high magnification (200×), showed spatial distributions and captured local tendencies. All parameters of hydraulic property of lognormal model (θ_e, ψ_m, and σ) had the same areas with large values caused by structural development. This means that WRCs had variabilities on the surface of the core samplers with 5-cm inner diameter. Relationships between magnification and WRC parameters were investigated. The θ_e and σ could be captured exactly at a magnification of 50×. In this study, ψ_m was underestimated by the image-based method at all magnifications. In conclusion, for estimating WRCs, image obtained at magnification of 50× showed the highest accuracy. However, images at 50× magnification could not capture the microscopic spatial distribution of soil pore structure.

Crop yield decline, primarily caused by soil erosion, is a major challenge in rain-fed agriculture. Massive soil and water conservation (SWC) practices are conducted each year in the country of Ethiopia, including the study sites, to tackle the problems, but there is not enough information about the impacts those practices on crop yields in the study area. The impacts of different soil conservation practices on finger millet yield (Eleusine coracana (L.) Gaertn.) were evaluated on conserved and non-conserved croplands during the 2021/2022 cropping season. The experimental fields were blocked based on slope classes to account for topographic variation. A total of 27 plots having 3.2 × 3 m size were established. The highest plant height (73.24 cm), biomass yield (2.50 t ha⁻¹), and grain yield (1.57 t ha⁻¹) were recorded from soil bunds stabilized with grass. The interaction of conservation practices and slope gradient positively influenced plant height, biomass, and grain yield. Biological soil conservation practices + foot slope yielded the highest plant height (79.71 cm), biomass (3.08 t ha⁻¹), and grain yield (1.57 t ha⁻¹). The result showed that there was a significant difference of millet yield and yield components in conserved and non-conserved fields (p < 0.05). This study implies that implementing suitable soil conservation techniques based on slope characteristics is the best solution to improve finger millet yield in northwestern Ethiopia. It is recommended that farmers adopt slope-specific SWC measures, such as soil and grass-stabilized bunds, to reduce erosion and improve soil fertility and finger millet yield.