Agrosystems, Geosciences & Environment最新文献

Soil salinity is a global issue that impacts crop production and requires management to contain and ameliorate. Although field-scale assessments are limited, a recent strategy used to manage salinity in the Northern Great Plains is the wide-spread adoption of subsurface drainage. Therefore, a study was conducted between 2013 and 2021 on a 57-ha field in southeastern North Dakota where changes in soil salinity, groundwater quality, and grain yields (soybean [Glycine max], wheat [Triticum aestivum], and corn [Zea mays L]) were compared between subsurface tile drained (TD) and undrained (UD) areas at the field scale. Topsoil (0–15 cm) electrical conductivity of saturated paste extract (EC_e) decreased at a rate of 0.15 dS m⁻¹ year⁻¹ for TD but increased 0.03 dS m⁻¹ year⁻¹ for UD. The groundwater electrical conductivity of water (EC_w) decreased 0.5 and 0.3 dS m⁻¹ year⁻¹ for TD and UD, respectively. Soil EC_e, chloride (Cl⁻), sulfate-sulfur (SO₄²⁻-S), calcium (Ca²⁺), sodium (Na⁺), and magnesium (Mg²⁺) concentrations increased with soil depth for TD and UD. However, these ion concentrations decreased with time for TD and stayed relatively unchanged or increased for UD. Groundwater EC_w and ion concentrations decreased over time for TD and to a lesser extent for UD. Groundwater levels increased slightly for TD but increased more for UD, where high water tables caused wet soil conditions resulting in yield reduction in several years. Soybean yields increase by 0.18 and 0.06 Mg ha⁻¹ year⁻¹ for TD and UD, respectively. Wheat grain yield increased over time for TD and UD at similar rates (0.17 and 0.18 Mg ha⁻¹ year⁻¹, respectively). Corn grain yield increased slightly from 2016 to 2019 for TD, but decreased by 6.2 Mg ha⁻¹ from 2016 to 2019 for UD due to wet soil conditions. Overall, the outcomes of this field-scale study provide validation of similar outcomes reported in small-scale studies for subsurface drainage as a management tool for soil salinity in the Northern Great Plains.

The short-run effects of cover crop use on cash crop yields (e.g., corn [Zea mays L.] and soybeans [Glycine max (L.) Merr.]) have been a topic of debate given that evidence from previous literature has generally been mixed on this issue. Past studies suggest that the observed yield effect varies (i.e., negative, positive, or insignificant), often depending on the applied cover crop species used, weather conditions, and farm management practices implemented (among others). In this study, we examine the short-run (i.e., 1 year) yield impact of four different cover crop families—grasses (Poaceae), broadleaves (Brassicaceae), legumes (Fabaceae), and others—both as single-family groups and as mixtures. Data from side-by-side on-farm experimental plots in six Eastern US states were collected from 2017 to 2019 in order to achieve the objective of the study. Statistical analysis of this multi-year plot-level data suggests that the majority of the cover crop families and mixtures investigated in this study do not have a statistically significant short-run effect on subsequent corn yields. In some cases, cover crop treatment even resulted in short-run yield losses (i.e., a yield penalty). These results imply that cash crop yield benefits from cover crop adoption are likely not going to be observed with just 1 year of use. This lack of immediate economic benefit may explain the relatively low cover crop adoption rate currently observed in the United States and the need for upfront cost-share subsidy payments to encourage further uptake of this practice.

To meet the turfgrass standards that players expect, golf course superintendents rely on intense irrigation, fertilization, and cultivation programs. However, the overapplication of irrigation water and fertilizer has been shown to have negative effects on water quality. Precision turfgrass management (PTM) is an emerging area of interest as more golf course superintendents are looking to increase input efficiency while simultaneously reducing water and fertilizer input costs, as well as environmental impacts. Our objectives were to (1) use electromagnetic induction (EMI) to determine the spatial variability of apparent electrical conductivity (EC) in sand-capped fairways and (2) correlate EC to measured soil and turfgrass characteristics to determine the applicability of mapping EC for PTM. Soil samples and EC data were collected in spring 2021 on four sand-capped fairways from two golf courses (one hybrid bermudagrass and one zoysiagrass) belonging to the same facility in southeast Texas. Apparent EC was found to be positively and significantly correlated with soil volumetric water content (VWC, 0.40 < r > 0.62) and turfgrass normalized difference vegetation index (NDVI; 0.21 < r > 0.46) in three of four fairways, while EC was negatively and significantly correlated with penetration resistance (PR, −0.29 < r > −0.48) in two of four fairways studied. The strengths of these relationships were corroborated by strong visual similarities when comparing spatial maps of EC with those of VWC, NDVI, and PR, indicating that EMI-based EC data have potential for use in delineating site-specific management zones for water and fertilizer applications, as well as targeted aeration.

Arid and semiarid regions cover more than one-third of the land surface, where the interplay between water, land use, and management strongly influences carbon (C) sequestration. Yet, information on the C management practices and how local biophysical conditions affect the C sequestration potential is limited. We explored the opportunities, research gaps, and future directions of land C sequestration in arid and semiarid regions, using New Mexico as an example. We also identified the major land use types and their potential for C storage and sequestration. Our results showed that innovations in cropland and rangeland management, protection of existing forests, and restoration of degraded forest lands after drought and wildfire enhanced C sequestration in arid and semiarid lands. Landscape-scale C balance studies with fine-scale mapping, improving water and nutrient use efficiency, and policy incentives to support farms will unlock the full potential of C sequestration in croplands, rangelands, and forest lands. Future research should focus on the response of land management practices to climate anomalies and their potential to sequester C and offset greenhouse gas emissions as a natural climate solution in arid and semiarid regions.

Winter cereal rye (Secale cereale L.), a commonly used cover crop in corn (Zea mays L.) systems, has potential to scavenge soil NO₃–N through a fibrous root system. This study aimed to quantify root and shoot biomass, carbon (C), and nitrogen (N) partitioning in rye cover crop at the time of termination in spring. This was a 1-year study conducted at a site with a no-till corn–soybean [Glycine max (L.) Merr.] rotation, rye drilled following grain crop harvest, and three N rates applied to corn (0, 135, and 225 kg N ha⁻¹, respectively). Rye root biomass to 60-cm depth following corn and 30-cm depth following soybean was estimated using ingrowth tubes installed in the fall after rye seeding and removed at the time of rye termination in the spring. For rye, 48% and 62% of the total root biomass were present in the top 15-cm depth, following corn and soybean, respectively. Overall, the shoot biomass, C, and N were significantly greater than for roots, with approximately two times more shoot than root material and only 33%–36% of total plant C and 17%–18% of total plant N in the root biomass. The C:N ratio of root biomass was consistently high (47–52) and at least double that of the shoot (16–23). With high C, low N, and high C:N ratio of the rye roots, inorganic-N from soil or degrading shoot biomass could be immobilized with root degradation and reduce potential N recycling.

This study investigated the potential of different wheat varieties to influence the performance of the subsequent wheat crop. In fall 2021, a single variety of winter wheat (cv. Norwest Tandem) was planted into standing wheat stubble in plots that were previously planted to five winter wheat varieties. At harvest, yield was significantly affected by the variety that had been planted in each plot during the first year of the trial. Specifically, wheat following the variety Pritchett yielded approximately 12% more than wheat following the variety Bobtail. While planting the second crop, residue from the winter wheat variety Norwest Duet caused the no-till plot drill to plug (accumulate large amounts of soil and crop residue in front of openers) far more than residue from the other varieties. This indicates that varieties differ in their residue management requirements. These differences could be exploited to best fit different agricultural practices. This study highlights the potential importance of varietal effects that persist in the field after the field is harvested. However, more work is needed to understand varietal differences in residue management requirements and varietal effects of the successive crop before they can be fully leveraged in wheat breeding and genetics, wheat agronomy, variety testing programs, and eventually the producer's field.

Soil aggregate stability is an important soil physical measurement that is closely related to a range of soil health functions. It is defined by its analytical method and often within-method variability and inter-method comparability have not been addressed and quantified. The current Natural Resources Conservation Service Kellogg Soil Survey Laboratory (KSSL) method for analyzing aggregate stability uses non-standardized equipment and hand-sieving techniques and is not easily scalable. The objective of this study was to evaluate and modify an alternative method that uses a single sieve mechanical wet sieving apparatus (MWS method) to produce results comparable to the current KSSL method and evaluate another alternative method that uses multiple sieves in a custom-fabricated Yoder-type apparatus. The two methods were evaluated for efficiency, repeatability, and scalability. The MWS method uses standardized equipment and methods, which should be scalable and reproducible in different laboratories. Sample preparation, pretreatment, and sieving parameters of the MWS method were adjusted to produce analytical results which most closely matched the KSSL method. Repeated analysis of soil sample standards showed that within-method variability of the MWS method was slightly less than in the KSSL method. In a comparison of 90 samples of widely varying properties, Lin's concordance correlation coefficient was 0.927, indicating a moderate strength of agreement between the MWS method and KSSL method. Results from a modified Yoder method were not comparable to the KSSL method, and the greater time requirements, procedural complexity, and large equipment footprint were identified as practical limitations for use in large-scale laboratory applications.

Mulch from cover crops can suppress weeds and facilitate organic no-till corn and soybean production. However, research is lacking on the no-till planting small grain crops into rolled-crimped cover crops. An experiment was conducted to test the effects of no-till planting winter wheat (Triticum aestivum L.) into five cover crops planted in early summer, mid-summer, and late summer. Cover crops were terminated with a roller-crimper, and winter wheat was simultaneously no-till planted in early fall. A “no cover crop” control treatment was also included, where wheat was planted into tilled soil. Cover crop and weed biomass at wheat planting varied by cover crop planting date and species. Early-summer-planted sorghum sudangrass [Sorghum bicolor (L.) Moench × S. sudanense (Piper) Stapf.] produced the most cover crop biomass and had among the lowest weed biomass at wheat planting and wheat harvest. However, wheat seedling density and grain yield were relatively low in the early-planted sorghum sudangrass treatment compared with the other cover crop treatments, indicating a tradeoff between weed suppression and wheat yield. Early-planted buckwheat (Fagopyrum esculentum Moench) and early-planted soybean [Glycine max (L.) Merr.] had among the highest wheat grain yields, but no treatments yielded more than the “no cover crop” control. Wheat grain nitrogen was variable and may have been impacted by multiple factors, including wheat density. Results from this experiment indicate that rolled-crimped cover crops can facilitate organic no-till winter wheat production, but more research is needed to overcome tradeoffs and optimize production.

To sustain agriculture for future generations and reduce the adverse impacts on soil health and the environment, there is a need to adopt sustainable and climate-smart agricultural practices. A field experiment was conducted to study the effects of organic amendments (chicken and dairy manures and biochar) on the soil physicochemical properties, sweet corn (Zea mays) growth, and yield parameters at Prairie View A&M University, Texas. Two rates of biochar (2.5 and 5 t ha⁻¹) and two types of manure (chicken and dairy) applied at three rates (0, 224, and 448 kg total N ha⁻¹) were used in a factorial design with three replications. Plant height, period for each vegetative growth stage, leaf soil plant analysis development, time to reach 50% tasseling and 50% silking stage, cob length, cob diameter, sugar content, and biomass were measured. The results showed that plant biomass was significantly affected by biochar rate, while plant height, cob length, and cob diameter were significantly affected by manure rates. Sweet corn reached tasseling and silking stages earlier in chicken manure-treated plots than the dairy manure plots. However, the sugar content was significantly affected by both biochar and manure rates. Furthermore, results revealed a strong positive correlation between plant height and cob length, diameter, and biomass; however, there was a negative correlation with tasseling and silking days. Soil phosphorus, total nitrogen, and potassium had a relatively positive correlation with plant growth parameters. Findings showed that different types and rates of amendments significantly influenced sweet corn growth parameters and soil nutrient status, highlighting the importance of adopting climate-smart agricultural practices for improved crop yield and soil health.

This article presents an economic analysis of two phosphorus (P) fertilizer recommendation approaches, sufficiency and build-maintenance, in the context of Kansas and Oklahoma wheat (Triticum aestivum L.). Sufficiency seeks to meet crop needs rather than build soil fertility. Build-maintenance, however, builds P levels to a target level of soil test phosphorus (STP) and then maintains that level by replacing the P removed by the crop. The Oklahoma and Kansas sufficiency approaches recommend less P than their build-maintenance alternatives. The research objective was to determine when one approach is preferred over the other. Through dynamic simulation, the net present value (NPV) of these two alternatives was estimated under alternative scenarios. A meta-analysis of previous experiments supported the assumption that with Mehlich-3 STP levels of 15 mg kg^‒1, yield would be 90% of maximum yield even when the recommended sufficiency levels were applied. The estimate from the meta-analysis was a 9% yield loss, and the null hypothesis of no yield loss was rejected (p < 0.0001). The scenarios considered varied initial STP, yield potential, and prices. Sufficiency had a higher NPV under almost all 4-year planning horizons. With a longer 20-year planning horizon, build-maintenance was always preferred. With an 8-year planning horizon, the preferred system varied depending on assumptions with build-maintenance preferred more often. The finding of build maintenance being more competitive in the long run should hold for other crops and locations using approaches like those in Oklahoma and Kansas.