Agrosystems, Geosciences & Environment最新文献

Little information is available on optimizing the number of nitrogen (N) splits based on nitrate (NO₃-N) leaching and maize yield in sandy soils. To address this gap, we evaluated the impact of multiple N splits (2-, 3-, 4-, and 5-N splits) on NO₃-N leaching and maize (Zea mays L.) grain yield in irrigated loamy sand soil at a producer site in the Bazile Groundwater Management Area of Northeast Nebraska. Porous suction cup lysimeters were installed at a depth of 120 cm to collect pore water samples from 23 leaching events in 2021, a dry year. Increasing the number of N-splits did not affect the pore-water NO₃-N concentration; however, it was 169%, 152%, 150%, and 129% higher in 2-, 3-, 4-, and 5-N split treatments compared to control, that is, without N application. Though the 2-, 3-, 4-, and 5-N splits had 110%, 71%, 120%, and 91% higher area-based NO₃-N leaching than the control, less deep percolation and more evapotranspiration in control led to no significant differences in area-based NO₃-N leaching among all treatments. All N-splits resulted in higher maize yield, nitrogen use efficiency, plant N uptake, harvest index, and aboveground biomass than control; however, the number of N-splits did not affect these parameters. The inclusion of environmental cost reduced the return to nitrogen by 92–143 $ ha⁻¹ across all N-split treatments but did not significantly affect the differences among the splits. Overall, the results indicate that increasing the number of N-splits does not provide agronomic, economic, and environmental benefits in irrigated maize fields during a dry year.

California produces many key agricultural products in the United States. Current geospatial agricultural datasets are limited in mapping accuracy, spatial context, or observation period. This study uses machine learning and high-resolution imagery to produce a time series of crop maps to assess crop type trends and patterns across central California from 2005 to 2020. National Agriculture Imagery Program and Landsat imagery were used to classify nine crop types that are common in the study region: grain crops, field crops, rice, citrus and subtropical, deciduous fruit and nut, vineyard, berry and vegetable, pasture, and fallow/young perennial crop types. To create labeled data, we sampled 1253 fields and manually identified crop types for each examined year using high-resolution imagery and Landsat normalized difference vegetation index time series. We applied a random forest machine learning algorithm in Google Earth Engine. Results show that the mean overall classification accuracy of the nine-class map was 93.1%, with individual accuracies ranging from 99.3% (rice) to 89.5% (fallow/young perennial). Mann–Kendall trend tests showed significant (p < 0.05) declines in field crop and pasture area during the study period, while deciduous fruit and nut, citrus and subtropical, and fallow/young perennial crop types experienced significant increases. At an aggregate level, there was a general shift from annual crop types to perennial crop types. These data provide a 16-year time span of spatially explicit crop type classifications, trends, and patterns in central California that can be used to aid managers and decision makers for resource planning or hazard mitigation.

Understanding the trade-offs between improving turfgrass performance and seed production capacity would improve acceptance and accelerate the release of new perennial ryegrass (Lolium perenne L.) cultivars. An experiment was designed to measure the turfgrass quality, seed yield, and component traits among 20 perennial ryegrass entries grown in turfgrass and seed production swards at two locations in Minnesota, a seed production region of the United States. Turfgrass quality scores, when averaged across collection dates, were not strongly correlated with seed yield at either location. However, data from several individual turfgrass quality rating dates were moderately correlated with seed yield at both locations (p < 0.100). Within the dates that correlated with seed yield, turfgrass component traits were regressed against quality scores. Crown rust severity, color, and density were important in the first year, and winter injury and texture were important in the second year. Plots with more fertile tillers were associated with higher seed yield and lower turfgrass quality (p < 0.050), but there was no relationship between entries in the two growing environments for fertile tiller production (p > 0.250). Entries that exhibited a faster vertical growth rate in turfgrass swards tended to mature earlier in seed plots, a trait that was correlated with higher seed yield (p < 0.001). However, the vertical turfgrass growth rate was not directly correlated with seed yield (p > 0.800). Few tradeoffs between the growing environments were found under the growing conditions and germplasm employed.

Upland cotton (Gossypium hirsutum) production is important for the economy of the Texas High Plains (THP). This region of Texas is semi-arid and regularly experiences harsh weather conditions that can be difficult to predict. Some years, a cold front will pass through the area before local cotton crops have reached maturity and there are concerns that fiber maturation stops after these cold weather events. In 2020, fiber samples were collected at two locations on the THP (representing northern and southern cotton producing regions) before, during, and after a cold front (<10°C) moved through the area in September, which is a critical period for fiber maturation. Single boll samples were taken at New Deal, TX (representing a southern location) in the first position from nodes 5, 8, and 11. At Etter, TX (representing a northern location), 30-boll bulk samples were taken from first position bolls on nodes 5, 8, and 11. Advanced fiber information system testing determined the fiber quality of single boll samples. Lint weight in both locations continued to increase despite the cool temperatures. At New Deal, upper quartile length, length, short fiber content, seed coat neps, fineness, and maturity all saw significant improvements from before to after the cold front. This indicates that the bolls continued developing after exposure to cool temperatures on the THP.

Interseeding annual warm-season forages into perennial cool-season grasses may increase herbage mass and quality. Yet, methods to do so successfully remain elusive. From 2020 to 2022, we conducted an experiment that evaluated herbage mass responses to sod suppression after interseeding sorghum × sudangrass [Sorghum bicolor (L.) Moench × S. bicolor (L.) Moench ssp. drummondii (Nees ex Steud.) de Wet & Harlan] in three N-fertilized and three mixed-legume smooth bromegrass (Bromus inermis Leyss.) pastures. Sod suppression treatments included glyphosate [N-(phosphonomethyl) glycine] applications of 0, 0.55, 1.10, 1.65, and 2.20 kg ha⁻¹ on pastures that were heavily grazed in two rotational stocking periods in spring and an additional 0 kg ha⁻¹ glyphosate control where herbage was stockpiled throughout spring, mowed, and removed before interseeding sorghum × sudangrass. In herbage samples collected 8 weeks after treatment, perennial grass mass showed exponential decay responses as glyphosate rate increased, while sorghum × sudangrass, weedy grass, and total herbage mass showed logistic growth responses. Sorghum × sudangrass reached a high of 2316 kg ha⁻¹ as glyphosate rate increased to 1.65 kg ha⁻¹ while weedy grass mass continued to increase as glyphosate rate increased to 2.20 kg ha⁻¹. Reduced perennial grass mass in herbage samples collected the next spring indicated the presence of a tradeoff between increasing summer herbage now and reducing next spring herbage later with glyphosate application after interseeding sorghum × sudangrass. We concluded practitioners should not use glyphosate for sod suppression before interseeding warm-season annual forages into perennial cool-season grass pastures.

Repetitive use of heavy farm machinery in cultivated agriculture may cause soil compaction that can adversely affect soil-health-related properties. Cover crops (CC) are well-documented to alleviate problems associated with compaction and improve overall soil health in time. The objective of this field study was to evaluate the cumulative effects of CC treatment (i.e., with ≥ 6 years cereal rye [Secale cereale L.] CC and ≥ 4 years with no cover crop [NCC]) and sample/measurement placement (i.e., in the bed [B] and in the wheel-track [WT] and no-wheel-track [NWT] furrow) on near-surface soil physical-, chemical-, and infiltration-related properties in an alluvial soil under cotton (Gossypium hirsutum L.) production in the Lower Mississippi River Valley. Samples were collected and in-situ measurements were conducted in late May 2019 within a single field in eastern Arkansas. Overall-infiltration rate was two times greater (p ≤ 0.01) in B compared to WT and NWT placement, which did not differ. Soil bulk density in WT was 1.1 times greater than the other two placements, while soil organic matter was greater in CC-WT (30.7 Mg ha⁻¹) than in all other treatment-placement combinations, except for CC-NWT, which did not differ. Similarly, water-stable-aggregate concentration was 2.3 and 1.6 times greater in the CC-NWT and CC-WT combinations, respectively, which did not differ, compared to under NCC. Results demonstrated that CC benefits extended beyond the bed to positively affect soil properties in adjacent WT and NWT furrows. Continued small-scale, long-term management studies using CC will extend insight into site-specific, soil-health improvements.

Soil fertility depletion has significantly reduced the yields of various crops in Ethiopia, mainly the yield of malt barley in the district. To address this issue, integrated applications of vermicompost and mineral nitrogen (N) fertilizers were tested. Therefore, this study aimed to evaluate the effects of vermicompost and mineral nitrogen fertilizers application on malt barley yield (Hordeum distichum L.), soil properties, and economic benefits. The experiment was arranged in a randomized complete block design with three replications. The treatments were nine in various combinations of vermicompost (VC) and N fertilizer (N): (69 kg N; 0.79 t VC + 58.65 kg N; 1.59 t VC + 48.30 kg N; 2.39 t VC + 37.95 kg N; 3.19 t VC + 27.60 kg N; 3.98 t VC + 17.25 kg N; 4.78 t VC + 6.90 kg N; 5.31 t VC ha⁻¹ and control). The highest soil pH was recorded by applying 5.31 t of vermicompost ha⁻¹ alone. The highest total nitrogen (0.34%), available phosphorus (15.58 mg kg⁻¹), grain yield (4950 kg ha⁻¹), and net benefit (4255.74 USD) were recorded from the application of 2.39 t VC plus 37.95 kg N, while the highest soil organic carbon (3.38%) and cation exchange capacity (26.17 cmol (+) kg⁻¹) were recorded from 3.19 t VC plus 27.60 kg N ha⁻¹ compared to the control. This study concludes that applying 2.39 t VC and 37.95 kg N ha⁻¹ in combination improves soil fertility, malt barley yield, and economic benefits for smallholder farmers in the study district and adopts this in similar soil types and agroecologies.

In order to identify the effect of genotype × trait, 20 maize (Zea mays L.) hybrids were cultivated and investigated in a randomized complete block design in three replications in the Karaj region. The results of the analysis of variance showed that the effect of genotype in terms of all traits except for the traits of days until the tassel dries, peduncle outside the flag leaf, tassel length, the number of fill seeds, and the depth of the seeds are significantly different. Based on the mean comparison done by Duncan's method, G3, G6, G7, and G4 genotypes were identified as favorable hybrids. Based on the graphic analysis, the genotypes G5, G4, G6, G3, G9, and G14 can be identified as desirable hybrids. The correlation diagram indicated that the grain yield trait has a positive correlation with tassel length, leaf length, leaf width, and leaf surface traits. Based on the principal component analysis, the first 10 components explained more than 74% of the data variance. The traits were classified into 10 components: components of ear characteristics, time characteristics in terms of maturity, leaf characteristics, characteristics of maize plant 1 (cob corn diameter, peduncle length, and grain yield traits), characteristics of maize plant 2 (number of tassel branches, leaf surface, and grain yield traits), physiological characteristics and germination, the crown part of the ear characteristics, grain characteristics, grain yield, and characteristics of the ear head. The experiment results indicated that G8, G15, G1, and G6 hybrids were more favorable in terms of grain yield trait.

Environmental changes pose major impacts on the performance of crop genotypes with important implications for crop improvement strategies. Hence, breeders pay attention to the effects of genotype by environment interaction (GEI) to mine genetic resources and select adapted genotypes. Twenty sorghum genotypes selected from a large collection of Ethiopian sorghum landraces and two improved varieties were evaluated using a randomized complete block design with three replications at eight locations representing different environmental conditions in Ethiopia. The study aimed at assessing GEI and identifying stable and high-yielding genotypes of sorghum for grain yield and major agronomic traits. Analysis of variance and additive main effect and multiplicative interaction (AMMI) revealed highly significant (p ≤ 0.001) variance due to genotypes, environments, and GEI among all traits except for days to maturity. Plant height, days to maturity, panicle width, panicle weight, and grain yield were highly affected by environment and GEI, while days to flowering, panicle length, and 1000-grain weight were mainly affected by genotypic variations. The data also suggest the importance of considering GEI in screening for high-yielding and stable sorghum genotypes across environments. Among testing sites, Chawaka, Gute, and Uke were ideal environments for grain yield and Asosa was the most discriminative environment. Three genotypes (ETSL100808, Merera, and ETSL100474) were superior and stable across test environments for grain yield and related traits. Overall, based on mean grain yield and disease reaction, AMMI, GGE (genotype and genotype by environment interaction) biplot, and regression models, ETSL100808 was the most stable, high-yielding, and disease-tolerant sorghum genotype, suggesting its potential both in breeding program, as donor of traits, and for direct release as a variety.

The fundamental ecosystem processes in soil are regulated by microbial communities, and community diversity is implicated by soil environmental conditions. Humic acid (HA) improves soil quality and fertility, stimulating the microbial environment, but the detailed effects remain poorly understood. We investigated the effects of HA rates on soil bacterial diversity, particularly on species richness and community composition in the rhizosphere of corn (Zea mays). Inorganic fertilizer (T2), HA 0.5% (T3), HA 1.0% (T4), HA 1.5% (T5), and HA 2.0% (T6) were applied in soil. Initial soil (O1) and control after harvesting (T1) were included. A total of 3601 operational taxonomic units were captured from the overall sample, and analysis of 16S ribosomal ribonucleic acid amplicon sequencing data indicated that HA did not notably impact species richness. Intriguingly, HA induced changes in bacterial community composition, along with the relative prevalence of specific taxa. Certain associations between soil chemical properties and abundance distribution have been uncovered. Notably, exchangeable Mg²⁺, Ca²⁺, and available phosphorus were strongly related to the relative abundance of bacterial phyla. Furthermore, HA potentially shaped the specific bacterial taxa, as the application of HA at different rates had distinct effects on the member of bacterial abundance of each taxon. These findings enhance our understanding of communities potentially being increased or shifted by HA rate addition in short-term corn cultivation.