Agrosystems, Geosciences & Environment最新文献

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.

Integrated crop-livestock systems (ICLS) bring diversity to agricultural systems, enhancing soil ecosystem services, food production, and environmental sustainability. Resource utilization efficiency practices under semiarid ecoregions include dual systems that grow wheat (Triticum aestivum L.) for both grain and grazing (G) and recently complementary to wheat dual systems, cover crops (CC) for feeding both the soil and cattle during the fallow period. The latter continues to generate interest and there is a paucity of information on associated biochemical cycles. The objective was to evaluate the impact of CC and grazing thereof on soil microbiota structure, diversity, proliferation, and nutrient cycling. Introducing CC to no-till (NT [NTC]) and grazing CC (NTCG [ICLS]), increased total PLFA biomass (TPB) for ungrazed CC (NTC) by 12%, and grazed CC (NTCG [ICLS]) by 20%; total bacteria biomass (TBB) by 10% for NTC and 24% for NTCG; total fungal biomass (TFB) by 9% for NTC and 21% for NTCG. The CC significantly increased Gram (−) bacteria biomass by 17% and 34% for NTC and NTCG, respectively; the CC significantly increased Gram (+) bacteria biomass by 6% and 12% for NTC and NTCG, respectively; and the CC significantly increased arbuscular mycorrhizal fungi by 55% and 89% for NTC and NTCG respectively, compared to NT fallow practice. Significant correlations were observed for NO₃⁻–N, NH₄⁺–N, water-extractable organic nitrogen, total nitrogen, and water-extractable organic carbon with TPB, TBB, and TFB using Haney soil health methods. Based on the measured parameters, the soil health status decreased in the order NTCG > NTC > NT > CT, where NT is the no-till, C is the cover crop, G is the grazing, and CT is the conventional-till. Grazing CC enhanced soil bacterial biomass over CC in solitude.

With grower interest in skip and wide row cotton systems, varietal performance in such systems has become a major question. An experiment was conducted in 2022 and 2023 in Tifton and Midville, GA, evaluating three row arrangements (standard 91-cm row spacing, 2 × 1 skip row, and 183-cm row spacing or wide row) and four commercially available varieties (Stoneville [ST] 5091 Bollgard 3 Xtendflex [B3XF], Phytogen [PHY] 400 Widestrike 3 Roundup Flex Enlist [W3FE], DynaGro [DG] 3799 B3XF, and Deltapine [DP] 1840 B3XF). There were no interactions between variety and row arrangement for any response variable, indicating the best variety for standard row spacings would also be the best variety in alternative row arrangements. Plant populations were reduced 32% and 53% in 2 × 1 skip-row and wide-row systems, respectively, compared to standard row arrangements, which accomplishes the major goal of these systems in reducing seed cost. Boll rot and hard lock were reduced in wide row treatments only, which could benefit cotton growers in the lower Southeast. However, reductions in lint yield were associated with 2 × 1 skip row (all site years) and wide row arrangements (three out of four site-years) compared to the grower standard. Differences among varieties were observed in plant heights, lint yield, and fiber quality, which is to be expected. These results confirm much of the work conducted on skip and wide row cotton systems and indicate that for growers in the lower Southeast to achieve maximum lint yields, standard row arrangements are superior to alternative row arrangements.

This study uses a small unmanned aircraft system equipped with a multispectral sensor to assess various vegetation indices (VIs) for their potential to monitor iron deficiency chlorosis (IDC) in a grain sorghum (Sorghum bicolor L.) crop. IDC is a nutritional disorder that stunts a plants’ growth and causes its leaves to yellow due to an iron deficit. The objective of this project is to find the best VI to detect and monitor IDC. A series of flights were completed over the course of the growing season and processed using Structure-from-Motion photogrammetry to create orthorectified, multispectral reflectance maps in the red, green, red-edge, and near-infrared wavelengths. Ground data collection methods were used to analyze stress, chlorophyll levels, and grain yield, correlating them to the multispectral imagery for ground control and precise crop examination. The reflectance maps and soil-removed reflectance maps were used to calculate 25 VIs whose separability was then calculated using a two-class distance measure, determining which contained the largest separation between the pixels representing IDC and healthy vegetation. The field-acquired data were used to conclude which VIs achieved the best results for the dataset as a whole and at each level of IDC (low, moderate, and severe). It was concluded that the MERIS terrestrial chlorophyll index, normalized difference red-edge, and normalized green (NG) indices achieved the highest amount of separation between plants with IDC and healthy vegetation, with the NG reaching the highest levels of separability for both soil-included and soil-removed VIs.

Shade trees are important in cocoa agroforestry systems; however, they release allelochemicals from various parts that affect understory plants. Unfortunately, information on allelochemicals produced by shade tree bark in cocoa plantation remain scarce. This study investigates the effect of allelochemicals from bark of shade trees on cocoa seedlings growth. The experiment was a 4 × 11 factorial study, and the treatments were four different concentrations from each of the 11 tree species. The treatments were laid out in a completely randomized design with four replicates. Data were collected at 30, 60, 90, 120, and 150 days after treatment applications. The tree species alone and bark extract concentrations alone significantly impacted plant height from 90 to 150 days after application. Albizia ferruginea (Guill. & Perr.) Benth, Celtis mildbraedii Engl., and Triplochiton scleroxylon K. Schum produced the highest cocoa seedling heights. All concentrations also influenced stem diameter of cocoa seedlings. Albizia ferruginea enhanced stem diameter significantly among tree species and the control. Tree species and bark extract concentrations interacted to increase fresh root weights and dry plant biomass. Albizia ferruginea consistently increased dry plant biomass, while C. mildbraedii produced the highest enhancement for fresh roots. All concentrations enhanced plant biomass, with the 75 mg mL⁻¹ concentration consistently producing the highest plant fresh and dry weights. Albizia ferruginea and C. mildbraedii can be potential tree species in the cocoa agroforestry when 2-month-old cocoa seedlings are to be transplanted on the field. Bark extract of 75 mg mL⁻¹ concentration can be used as a growth stimulant on cocoa seedlings.