Agrosystems, Geosciences & Environment最新文献

Diverse patterns of climate and edaphic factors challenge detection of soil property change in the US Great Plains. Because detectable soil change can take decades, insights into the trajectory of soil properties frequently require long-term site monitoring and, where available, associated soil archives to enable comparisons with initial or baseline states. Unfortunately, few multi-decadal soil change investigations have been conducted in this region. Here, we document effects of dryland cropping on a suite of soil properties by comparing matched historic (1947) and contemporary (2018) soil samples from the Haas Soil Archive at three sites in the US Great Plains: Moccasin, MT, Akron, CO, and Big Spring, TX. Current analytical methods were used to provide insight into changes in soil texture, pH, carbon, and micronutrients at 0- to 15.2-cm and 15.2- to 30.5-cm depths. Changes in direction and magnitude of soil properties over 71 years were site specific. Changes in textural class occurred at all sites, with Moccasin and Akron transitioning from loam to clay loam and Big Spring from sandy clay loam to sandy loam. The soil pH reaction class changed from slightly alkaline to moderately acid at Akron and slightly alkaline to moderately alkaline at Big Spring. At 0–15.2 cm, soil organic carbon decreased by 15% and 36% at Moccasin and Big Spring, respectively, but increased by 15% at Akron. Soil micronutrients generally declined at all sites. Weather-related variables derived from air temperature and precipitation records were not correlated with soil change. Inferred factors contributing to soil change included on-site management, inherent soil features, weather metrics not evaluated, or a combination thereof.

Soils contribute 15%–75% of total atmospheric nitrogen oxide (NO_x) emissions in agricultural regions during the growing season. However, the impacts of cropland fertilizer management on spatially heterogeneous, temporally episodic NO_x emission patterns are highly uncertain. We examine the effects of liquid slurry dairy manure application practices on soil NO_x emissions in rainfed, corn-soybean rotations during spring 2016 and 2017. Daily soil NO_x emissions and weekly soil inorganic N measurements were performed in a randomized split–split plot design for 1–4 weeks following manure applications. NO_x emissions and soil N with shallow-disk injection and chisel-disk manure incorporation methods were compared with unincorporated broadcast practices. Injected manure and chisel-disk incorporation exhibited two–four times larger mean NO_x emissions than those with unincorporated broadcast manure. Larger soil NO_x emissions with manure incorporation practices were driven by the predominance of nitrification in these treatments with evidence of soil nitrate production. Soil NO_x emission differences between treatments were detectable across order of magnitude changes in daily NO_x emissions during two growing seasons. Larger soil NO_x emissions associated with manure incorporation practices compared with unincorporated broadcast practices occur alongside larger N₂O and smaller NH₃ emissions, highlighting important air quality and climate impact tradeoffs for cropland manure fertilizer management choices.

Soil health is pivotal to agricultural sustainability. Promoting and sustaining soil health management is challenging since it involves many interdependent components and steps and is an iterative process. Herein, the soil health cycle (SHC) is proposed as a soil health management cycle encompassing human dimensions, management practices, and their effects on soil health indicators (SHIs), leading to subsequent impacts on soil functions. The SHC provides a structure for an iterative testing of changes to improve soil health. A systematic review of research publications was also conducted using the Web of Science database supplemented by Elicit AI and Scopus API searches to determine the status of research reports connecting SHIs to soil function outcomes, a critical component in the SHC. The review focused on publications from 2000 to 2022 and highlighted that most soil health studies separately report the potential roles of soil health practices such as cover cropping, no-tillage or reduced tillage, crop rotation, and crop–livestock integration in improving SHIs or soil function outcomes such as productivity and sustainability. The confidence in the causality of improved SHIs due to practices can be increased by demonstrably linking them to soil function outcomes such as productivity, environmental quality, and profitability. Presenting such evidence might allow us to tease confounding factors apart and present and contextually recommend soil health practices. It will also affect the human dimension in the SHC through informed and beneficial policies and incentives.

Soil inundation frequency and intensity in the central United States are predicted to increase because of climate change. Soil inundation is expected to negatively affect plant growth and persistency. Our objective was to measure tiller and apical meristem height, leaf area index (LAI), and leaf-to-stem ratio effects on tall fescue (Schedonorus arundinaceus (Schreb.)) under different levels of soil inundation intensity. The study was conducted on a commercial farm in northwestern Ohio, from spring to fall 2021. Three different levels of inundation were observed and assigned as treatments: no inundation, low inundation (LI), and high inundation (HI). LI and HI were defined by the duration on which the soil was inundated after heavy rain events: 1–2 and 3–5 days after rain, respectively. Meristem and tiller height were higher during spring (p < 0.001), and lower in late summer across treatments (p < 0.001). The higher LAI and leaf-to-stem ratio occurred in spring, probably due to higher leaf mass (p < 0.001). As seasons progressed, plant and meristem height, LAI, and leaf mass decreased (p < 0.001). Despite not being considered an inundation-tolerant species, tall fescue showed morphological adaptation to the inundation levels of our study, suggesting that this species can be used to manage fields prone to short-term inundation.

Crops such as quinoa (Chenopodium quinoa Willd.) that are both salinity and drought-tolerant and with high seed value are needed to sustain agriculture in arid Far West Texas facing dual threat of freshwater scarcity and soil salinization. However, quinoa's growth and yield performance under arid conditions of Far West Texas has not been studied previously. This study evaluated growth and yield of a salt-tolerant quinoa genotype under greenhouse conditions using a completely randomized experimental design with irrigation water salinity as the main factor having five different levels (freshwater, 5, 10, 15, and 20 dS m⁻¹). Plant parameters (plant height, leaf SPAD, leaf tissue carbon, and nitrogen concentrations) and seed yield were measured for two growing seasons. Soil quality (salinity and sodicity) changes were also determined for the same time. Seed yields ranged between 747 and 6065 kg ha⁻¹ across 2 years, indicating significant effects of water salinity. However, these yields were comparable to those reported in the literature. Increasing water salinity significantly affected all growth parameters with leaf C and N decreasing by an average of 20%, whereas reductions in plant height reached a high of 60% at 20 dS m⁻¹. Similar reductions in leaf chlorophyll content were found with increasing water salinity. Soil salinity and sodicity significantly increased over time with irrigation water salinity. Importantly, we observed that quinoa has a much higher soil salinity threshold (∼12 dS m⁻¹) above which yields declined rapidly. Higher salt tolerance threshold of quinoa makes it an alternative economically viable crop for the Trans-Pecos Texas region.

Rice (Oryza sativa L.) production in the Mid-Southern United States has traditionally been under conventional flood (CF) production, namely, direct-seeded and delayed-flood production. However, furrow-irrigated rice (FIR) has grown to comprise over 15% of Arkansas’ and 30% of Missouri's rice hectarage. The uptake of several nutrients, including phosphorus (P), potassium (K), and zinc (Zn), has been shown to differ between aerobic and flooded rice production. Hence, a nutrient uptake survey was conducted from 2018 to 2020 in FIR fields to determine the difference in nutrient uptake (macro- and micronutrients) between the upper generally aerobic environment at the top of the field and the bottom of the field, where a generally anaerobic or flooded environment existed from R1 to maturity. Aboveground biomass samples were taken at R3 from four nitrogen (N) treatments at the top and bottom of five sites on a clayey soil texture and four sites on a loamy soil texture. Results suggest that there is significantly lower P, K, sodium (Na), and manganese (Mn) uptake at the top of the field compared to the bottom of the field on both soil textures. Additionally, the N treatments that yielded the highest biomass generally led to the greatest uptake of all nutrients examined. The decrease in P and K uptake in the aerobic portion of an FIR field suggests that they may require altered fertilizer recommendations compared to the traditional CF rice system.

Commercial cultivars with advanced technology have reduced pest pressures, while greater seed costs have increased total production cost. Limited information is available on the optimal final population density (PD) for the commercially available cotton (Gossypium hirsutum L.) cultivars with advanced technologies in water-scarce environments. Therefore, our objectives were to examine the effects of PD on cotton growth and development, lint yield, fiber quality, and net return. A 2-year study was conducted to test four PDs (low, medium, high, and very high) in deficit-irrigated and dryland conditions at Chillicothe, TX. Final PD at 12 days after planting were 54,078, 109,563, 124,037, and 151,377 plant ha⁻¹ in irrigated and 67,346, 115,335, 116,397, and 145,432 plant ha⁻¹ in dryland trials. Maturity was delayed in the low PD early in the season; however, the differences on maturity ceased toward the end of the season. No statistical differences were observed on lint yield and fiber quality among treatments in irrigated and dryland trials. Average lint yields were 1199 kg ha⁻¹ in irrigated and 796 kg ha⁻¹ in dryland trial. Net returns were similar among all PD in the irrigated trial, while low PD had significantly higher net-return than very high PD in the dryland trial. The higher net return at the low PD was due to the lower seed cost associated with a low seeding rate. In the water-scarce environment, final plant density of 54,078 plant ha⁻¹ in deficit irrigation and 67,346 plant ha⁻¹ in dryland produced optimal yield and net return as compared to higher PD examined.

The interplay of management decisions involving soybean (Glycine max L.) planting date, herbicide programs, and herbicide application timings is critical to optimize soybean performance and weed control in Southern Great Plains soybean production systems. This research sought to evaluate soybean yield potential and the level of weed control as influenced by early-, delayed-, and late- planting dates and various combinations of preemergence (PRE), early-postemergence (EPOST), and mid-postemergence (MPOST) weed management programs. A field study was established in Bixby, OK in 2017 and 2018 under irrigated conditions and in Perkins, OK in 2017 under dryland conditions, consisting of three planting windows (early, delayed, and late) of XtendFlex soybean, with or without a PRE (chlorimuron + flumioxazin + pyroxasulfone + glyphosate + dicamba) combined with EPOST or EPOST + MPOST (glyphosate + dicamba) versus no in-season applications. The gap in late-planted soybean yield potential, compared to early-planted soybean, was exacerbated in the dryland systems (1346 kg ha⁻¹) versus an irrigated system (2311 kg ha⁻¹). Use of PRE provided 60% weed control until MPOST and increased yields by 657 kg ha⁻¹ and 457 kg ha⁻¹ for delayed and late-planted soybean, respectively. Late-planted soybean with EPOST + MPOST provided up to 50% weed control, but lack of biomass production for cultural control reduced weed control by 29% compared to early- and delayed-planted soybean. From an agronomic management standpoint, the time of soybean planting is influential on the success of weed control measures and soybean yields in double-cropping system in the Southern Great Plains, particularly with late-planted soybean.

Teff [Eragrostis tef (Zucc.) Trotter] grass has gained popularity in the United States as an emergency summer forage for livestock due to its drought tolerance and rapid growth habit. An alternative forage would benefit Texas Rolling Plains growers due to the summer forage shortage caused by drought conditions. However, among the teff research conducted in the United States, there is great variability in the forage yields and nutritive values depending on the amount of nitrogen and available water. The objective of the study was to evaluate forage productivity and nutritive value of teff in the Texas Rolling Plains under irrigated and dryland conditions with two nitrogen rates and application timings. Nitrogen fertilizer treatments included single applications of either 50 or 100 lb a⁻¹ applied at planting and a split application of either 50 or 100 lb a⁻¹ applied both at planting and after the first harvest. No differences were observed among nitrogen rates and application methods in the irrigated trial (5286 lb a⁻¹). The split application of 100 lb a⁻¹ produced the greatest total yield in the dryland trial (3096 lb a⁻¹) with no yield advantage of 100 lb N a⁻¹ over 50 lb N a⁻¹ at the first cutting. Forage nutritive values were similar to the warm-season forage species utilized in the region. This study showed that teff can be an alternative forage species in the region. Future research will include planting dates, nitrogen application timing, cutting height, and the interaction of these factors on yield and nutritive values of teff.