Grass Plots Research Articles

Effects of Different Land Uses and Slope on Runoff and Soil Loss on the Loess Plateau of China

ABSTRACTThe Loess Plateau has one of the most serious areas of soil erosion in China; therefore, studying the effect of soil and water conservation measures on the erosion of loess soil slopes is important for land management and agricultural development. This study is based on 5 years of field runoff observations and rainfall data from 2015 to 2019. Correlation and regression analyses were used to study the runoff and sediment production of loess soil and its relationship with rainfall, slope and land use. The results show that > 80% of the erosive rainfall occurs mainly in July to August in the area. Runoff and soil loss from the plots differed substantially, depending on land use, soil conservation measures and slope degree. Bare plots experienced the highest soil loss rate of over 27 t/ha with higher runoff depth, followed by cultivated plots (4.55 t/ha), grass plots (0.43 t/ha), shrub plots (0.35 t/ha) and forest plots (0.13 t/ha). Among the four soil and water conservation measures, the runoff and sediment reduction benefits of forest and shrub plots were the highest. The runoff reduction benefit fluctuated at approximately 0.8, and the benefit of sediment reduction was ≈1. The overall performance was forest > shrubland > grassland > cultivated land > bare land, and the benefits of sediment reduction were greater than those of runoff reduction. Forests had the highest soil retention capacity on slopes from 5° to 25°, and forests on gentle slopes had the best water storage capacity. Shrub plots had the best water storage capacity when they were on steep slopes. Rainfall erosion forces were significantly and positively correlated (p < 0.01) with runoff depth and soil loss, making it the most significant rainfall indicator of sediment production. Under the same rainfall conditions, soil and water conservation measures are still required on bare slopes, land use is the main control factor for slope sediment production, and appropriate land use can greatly reduce the threat of slopes in terms of soil erosion. This study shows that soil and water conservation measures are imperative to prevent runoff and soil loss, especially for bare land without any measures; on steep slopes, a vegetation combination primarily featuring shrubs is expected to achieve greater benefits in reducing runoff and sediment. This study can provide a scientific basis for the management of vegetation measures and the implementation of soil and water conservation measures on loess soil slopes.

First Report of Basal Stem Rot of Achnatherum inebrians Caused by Fusarium pseudograminearum in China.

Drunken horse grass (Achnatherum inebrians) is a perennial bunchgrass that is widely distributed in arid and semi-arid grasslands in northwest China (Zhang et al., 2021). In July 2023, Basal stem rot was found in artificially grown drunken horse grass plots in Yuzhong County (35.85° N, 104.12° E), Gansu Province, China, with an average incidence of 5.2%. Diseased plants showed crown and basal stem rot with chocolate brown discoloration at the base of the stem and slight constriction of some basal stems. Five field's foci were surveyed and at least 6 basal stems per focus were collected. Infected basal stems were surface-sterilized (75% ethanol for 30 s and 1% NaClO for 90 s), rinsed three times with sterilized water, placed on potato dextrose agar (PDA), and incubated at 22°C in the dark for 3 days. Isolates were purified by single spore cultures (Leslie and Summerell, 2006). The average mycelial growth rate was 4.8 to 7.5 mm/day at 25°C on PDA, and the colonies produced aerial mycelium varying from rose to yellow white, and rose to burgundy pigment diffused into the agar. Macroconidia of the isolates were produced on carnation leaf agar (CLA) incubated under black light and observed to be abundant, but no microconidia were found. Macroconidia were relatively slender, curved to almost straight, commonly 3-6 septate, averaging 30.1 × 3.8 μm (n=50). The morphological characteristics of this fungus fully fit the description of F. pseudograminearum (Aoki and O'Donnell, 1999). To obtain the phylogenetic support, DNA of three representative isolates YZ-Y-1, YZ-Y-2 and YZ-Y-3 was extracted by using an HP Fungal DNA Kit (D3195), and a portion of the RNA polymerase II second largest subunit (RPB2) gene and elongation factor 1 alpha (EF1-α) gene were amplified using primers RPB2-5f2 and RPB2-7cr (O'Donnell et al. 2010) and EF1 and EF2 (O'Donnell et al. 1998), respectively. Results of sequences were deposited in GenBank (accession nos. PP179044 to PP179049). A nucleotide BLAST search revealed RPB2 and EF1-α sequences to be 99.8 and 100% similar to the corresponding sequences of the ex-type strain NRRL 28062 F. pseudograminearum accessions numbers MW233433 and MW233090, respectively. For pathogenicity tests, 15 μl of conidia suspension (1×106 conidia/ml) was inoculated into the stem bases of 10 healthy drunken horse grass seedlings (around 3 weeks old) using a sterile syringe, then wrapped with moistened sterile gauze, while the other 10 drunken horse grass seedlings were injected with sterile water as a control. All seedlings were placed in a greenhouse with a plastic cover at 15-22°C and 90-100% relative humidity. All inoculated drunken horse grass seedlings showed symptoms similar to those of natural infection with stem basal rot, whereas uninoculated drunken horse grass seedlings remained healthy after 15 days. Fungi re-isolated from the basal stems of inoculated plants were confirmed phenotypically and molecularly as F. pseudograminearum. To our knowledge, this is the first report of F. pseudograminearum causing crown rot of drunken horse grass in China. The disease has become a potential threat to the growth of drunken horse grass in China.

Physiological and psychological recovery in two pure forests: interaction between perception methods and perception durations.

The forest experience is good for people's physical and mental health. However, few studies on the effects of pure forest based on the duration and way of experience on people's physical and mental recovery. In this study, we took 180 first-year college students as research objects and conducted experiments in Pinus sylvestris and Betula platyphylla and the control group of grass plot. The changes of physiological and psychological indexes of the subjects were compared by two perception methods (onsite perception, video perception) and three perception duration (10 min, 20 min, 30 min). The results indicated that: (1) Differences between the two pure forests were mainly reflected in short-term recovery of diastolic blood pressure (DBP) and long-term recovery of total mood disorder (TMD). (2) Video perception was more conducive to short-term recovery of systolic blood pressure (SBP) and diastolic blood pressure (DBP). (3) Viewing the Pinus sylvestris for 20 min in different ways was the best way to relieve stress. It is suggested that, Pinus sylvestris can be used as the rehabilitation perception material, and reasonable path length or perception time can be selected for landscape construction in future. These results can provide scientific reference for landscape design based on forest health and environmental perception.

Spike Device with Worm Gear Unit for Driving Wheels to Improve the Traction Performance of Compact Tractors on Grass Plots

In general, energy loss reduction via the interaction of tires with the ground improves tractor traction performance when a drawbar pull is generated. This paper is examines the driving wheels with steel spikes for a tractor equipped with modern radial tires. An improved design of the spike device that allows for the change between an active and inactive position of the spikes is presented. The traction performance of a compact articulated tractor with the spike device was tested on a grass plot with two soil moisture contents (SMC). The highest difference in the drawbar pull in the range from 14.2% to 40.5% and from 17.1% to 36.8% was reached by the spikes in the active position in comparison with the tires without spikes, which were at the slip range from 45% to 5% in the case of the low SMC when the test tractor was in the 3rd and 1st gear. The motion resistance difference between the spikes in the active position and the tires without spikes was 11.8% and 2.5% at the low and medium SMC, respectively. At the low and medium SMC, the highest tractive efficiency of 0.765 (0.721) and 0.757 (0.731) was reached by the spikes in the active position when the test tractor was in the 1st (3rd) gear in comparison with 0.736 (0.7) and 0.723 (0.708) in the case of the tires without spikes. The results indicated that the spike device allowed for the improvement of tractor tractive performance.

Biology of the non-parasitic phase of the cattle tick Rhipicephalus (Boophilus) microplus in an area of Amazon influence

BackgroundRhipicephalus (Boophilus) microplus is the most important tick species affecting cattle in the world. Under field conditions, the non-parasitic phase of R. (B.) microplus is unknown in the Amazon biome, including Brazil. The present study aimed to evaluate the non-parasitic phase of R. (B.) microplus in field (grass plots) and laboratory conditions.MethodsThe study was conducted from September 2020 to April 2022 in an Amazonian region (Maranhão State, Brazil). We evaluated the biological parameters of R. (B.) microplus under laboratory and field conditions. Engorged females were exposed to experimental conditions every 14 days, totaling 20 months of study. The following biological parameters were observed: pre-oviposition period, egg mass incubation period, and maximum larval survival period.ResultsAbiotic data (e.g., temperature and humidity) varied little throughout the year. Precipitation was the factor that varied the most throughout the year (dry ~ 30 mm3 and rain 400 mm3), and the parameters of pre-oviposition and pre-hatching are longer during the rainy season. A possible negative effect of the dry season on the percentage of hatched eggs was observed. Larval longevity in the plots of both control and free females was short (mean ~ 50–60 days), below that recorded for larvae under controlled conditions (mean ~ 95 days).ConclusionsRhipicephalus (Boophilus) microplus was able to complete its non-parasitic phase by producing host-seeking larvae in the pasture during all months of the study. The results indicate that R. (B.) microplus can complete up to six generations per year in biome Amazon. To our knowledge, this is the highest number of annual generations for R. (B.) microplus in Latin America.Graphical

Participatory Demonstration of Pennisetum pedicelluatum and Elephant grass (Pennisetum purpureum) Strip as Biological Soil and Water Conservation Measures for Erosion Control

On three beneficiary farmer fields, prescaling up and participatory demonstration of biological soil conservation techniques using Desho (Pennisetum pedicelluatum) and Elephant grass (Pennisetum purpureum) were carried out in 2019/2020 in comparison with control (no grass) activities. Assessing the role of biological conservation techniques in reducing soil erosion and farmers' opinions of these techniques was the primary goal. A total of 132 m2 demonstration plots were used to collect and analyze the experimental data. Elephant grasses (134 tons/ha) and desho (61.1 tons/ha) differed significantly (P < 0.05) in the second year. Elephant grass provided an average soil loss of 6.6 tons/ha/yr-1, desho grass produced an average of 10.9 tons/ha/yr-1, and control provided an average of 13.4 tons/ha/yr.The elephant grass plots showed the least amount of nutrient loss, while the control plots showed the greatest amount.When compared to Desho grass, elephant grass has a higher potential to control soil loss due to its robust root system and to rebound quickly, even in the event of a severe drought.Furthermore, because elephant grass grows quickly and has the largest freshweight biomass of any grass, farmers gave it more consideration in their assessments of grass strips than they did Desho grass.In order to improve acceptability and spread of the technology in dry land areas with a 5% slope for managing soil and nutrient losses, it is best to scale up elephant grass on a bigger scale. The highest nutrient loss was observed on the control plots and the least on the elephant grass plots. Based on the study results, elephant grass has a high potential to control soil loss through a strong root system and recovery immediately, even under severe drought conditions, compared with Desho grass. Additionally, farmers' evaluations of grass strips showed a higher attention to elephant grass than Desho grass due to the fast-growing nature of the grass and their highest fresh-weight biomass. Finally, it is better to scale up elephant grass on a larger scale to enhance acceptance and diffusion of the technology in dry land areas on a slope of 5% for controlling soil and nutrient losses.
 Keywords: Biological soil and water conservation, Desho grass, soil and nutrient loss

Feasibility Assessment of a Magnetic Layer Detection Method for Field Applications

The lack of current data on the spatial distribution of soil erosion hinders the ability to predict soil erosion on slopes. To address this problem, we present a simple and sensitive soil erosion measurement method called the magnetic layer detection (MLD) method. This method can measure the changes in soil layer thickness (SLT) at a site featuring a pre-buried magnetic layer (ML) using the relationship between magnetic susceptibility and soil thickness, and then use this information to determine the erosion or accumulation at that point. To verify the adaptability and accuracy of this method, we designed three field tests. First, we conducted a simulated sediment siltation experiment using the erosion pin (EP) method as the control. This experiment demonstrated the accuracy of the MLD method for measuring SLT (Rad2 = 0.97, NSE = 88.14%, and RMSE = 1.17 mm). Next, a simulated rainfall experiment with the runoff plot (RP) method as a control was used to demonstrate the effectiveness of the MLD method under water erosion. The results demonstrated that this method can reliably estimate soil erosion on both bare plots (Rad2 = 0.83, NSE = 71.78%, and RMSE = 0.56 mm) and sparse grass plots (Rad2 = 0.90, NSE = 81.77%, and RMSE = 0.25 mm), with performance that is better than that of the traditional EP method. Finally, a soil scouring experiment, again with the RP method as a control, was designed to verify whether the MLD method could accurately measure the erosion of a slope after the soil was scoured by surface runoff. The MLD method could accurately measure the slope erosion (Rad2 = 0.91, NSE = 89.55%, and RMSE = 0.42 mm), with results superior to those of the traditional EP method. The MLD method’s results were similar to those from the laser scanner (LS) method, but more accurate and with less associated cost and data processing time. Therefore, the MLD method has potential as a reliable measurement method that can provide useful guidance for elucidating the spatial distribution of soil erosion and predicting slope soil erosion. This approach could be used to obtain raw data to quantify soil erosion on the Loess Plateau of China and beyond.

Examination of the parameters controlling the triple oxygen isotope composition of grass leaf water and phytoliths at a Mediterranean site: a model–data approach

Abstract. Triple oxygen isotopes (17O-excess) of water are useful to trace evaporation at the soil–plant–atmosphere interface. The 17O-excess of plant silica, i.e., phytoliths, inherited from leaf water, was previously calibrated in growth chambers as a proxy of atmospheric relative humidity (RH). Here, using a model–data approach, we examine the parameters that control the triple oxygen isotope composition of bulk grass leaf water and phytoliths in natura, at the O3HP experimental platform located in the French Mediterranean area. A grass plot was equipped to measure for 1 year, all environmental and plant physiological parameters relevant for modeling the isotope composition of the grass leaf water. In particular, the triple oxygen and hydrogen isotope composition of atmospheric water vapor above the grass was measured continuously using a cavity ring-down spectrometer, and the grass leaf temperature was monitored at plot scale using an infrared (IR) radiometer. Grass leaves were collected in different seasons of the year and over a 24 h period in June. Grass leaf water was extracted by cryogenic vacuum distillation and analyzed by isotope ratio mass spectrometry (IRMS). Phytoliths were analyzed by IR–laser fluorination–IRMS after chemical extraction. We showed that the traditional Craig–Gordon steady-state model modified for grass leaves reliably predicts the triple oxygen isotope composition of leaf water during daytime but is sensitive to uncertainties on the leaf-to-air temperature difference. Deviations from isotope steady state at night are well represented in the triple oxygen isotope system and predictable by a non-steady-state model. The 17O-excess of phytoliths confirms the applicability of the 17O-excessphyto vs. RH equation established in previous growth chamber experiments. Further, it recorded average daytime RH over the growth period rather than daily RH, related to low transpiration and silicification during the night. This model–data approach highlights the utility of the triple oxygen isotope system to improve the understanding of water exchange at the soil–plant–atmosphere interface. The in natura experiment underlines the applicability of 17O-excess of phytoliths as a RH proxy.

Effect of application rate of sodium nitrite and hexamine on the fermentation and the chemical composition of guinea grass silage harvested at different stages of maturity

Grass ensilability varies with maturity stage, mainly due to changing concentrations of dry matter and soluble carbohydrates with progressing forage maturity. Consequently, the required dose of silage additive to prevent the development of undesirable microorganisms may change with maturity stage. The objective of this study was to verify whether the application rate of an additive containing sodium nitrite and hexamine interacts with guinea grass maturity to alter silage fermentation and chemical composition. Four fields of guinea grass (0.5–0.7 ha each field) were mowed and divided into two plots per field. After 5 wk, one plot of each field was mowed again to establish differences in stage of maturity. Ten weeks after the first mowing, the grass plots with 5- and 10-wk regrowth were manually harvested and used for the trial. The grass from each plot (approx. 30 kg) was chopped and divided into 3 piles, totaling to 24 piles, as result of four fields, two maturities, and three additive treatments: control (without additive), low dose of sodium nitrite (0.5 g/kg) + hexamine (0.325 g/kg) (NHL), and high dose of sodium nitrite (1 g/kg) + hexamine (0.65 g/kg) (NHH). After 90 d of storage, the silos were opened and silages sampled to determine dry matter (DM) loss, microbial counts, fermentation end-products, aerobic stability, chemical composition, and in vitro DM digestibility. Guinea grass harvested at 10-wk regrowth had a lower content of crude protein (P < 0.001) and a greater content of cell wall components (P < 0.001), resulting in a more lignified (P < 0.001) and less digestible (P < 0.001) forage than that harvested at 5 wk. There were interactions between plant maturity and additive dose for several silage traits (P < 0.05), likely due to the slightly greater fermentability coefficient (+5.1 points) for the more mature grass (P < 0.001). Within each maturity stage, silage pH and fermentation end-products associated with clostridia metabolism (i.e., n-butyric acid, propionic acid, i-butyric acid, i-valeric acid, n-valeric acid, ammonia, and 2,3-butanediol) linearly decreased (P < 0.001) with additive application rate, but the magnitude of improvement was slightly greater for 5-wk than 10-wk regrowth. Application of additive linearly decreased silage DM loss at both 5-wk (95.2, 46.7, and 20.6 g/kg DM, P < 0.001) and 10-wk (66.5, 31.7, and 13.6 g/kg DM, P < 0.001) regrowth stages, but only silages treated with NHH had n-butyric acid concentration < 3 g/kg DM. The proportion of rumen undegradable protein (P < 0.001), soluble carbohydrates concentration (P < 0.001), and in vitro DM digestibility (P < 0.001) were linearly increased with additive dose within each maturity stage. As treated silages were better conserved, silage aerobic stability was linearly reduced (P < 0.001) with additive dose, although all silages were aerobically stable for ≥ 4.7 d. In conclusion, the additive based on sodium nitrite and hexamine, applied at a regular dose, was able to largely restrict Clostridium development and DM losses during fermentation of guinea grass silage at both maturity stages. However, harvesting more mature grass markedly impaired its chemical composition and digestibility, rendering it no feasible strategy to reduce the additive application rate by half.

105 Botanical composition, yield, horse preference, and forage and soil nutrient values of grass pastures treated with different soil amendments

Forage is the foundation of a horse's diet, therefore, pasture management is critical to improve horse health and pasture productivity. The objective of this study was to evaluate botanical composition, horse preference, yield, and forage and soil nutrient values of pasture treated with horse manure, horse compost, commercial urea fertilizer, and a no amendment control. Researchers hypothesized soil amendments would increase soil nutrients and yield with minimal effects on botanical composition, preference and forage nutrient value. Replicated (n = 3) plots of established cool-season mixed grass pasture were 3 × 6 m and located in St. Paul, Minnesota. The soil was a Waukegan silt loam with a pH of 6.4 and 47 g kg–1 organic matter. Urea was applied based on initial soil test recommendations, 0.64 cm of compost was applied based on common recommendations, and manure was applied at a rate to represent horse manure deposition in May 2022. Sample collection and grazing periods occurred in May, June, July, August, and October 2022, each over a 2-d period. Botanical composition, average forage height and maturity, soil samples, forage samples, and forage yield were taken immediately before grazing. Horses were allowed to graze all plots for 4 h with preference visuallyassessed at 2- and 4 h post-grazing based on percent removal. Data were analyzed as a randomized complete block design using PROC MIXED in SAS with significance set at P ≤ 0.05. Season-long yield ranged from 2,690 to 3,363 kg DM ha-1 and did not differ across treatments (P > 0.05). Botanical composition differed across treatments with the control having the most weeds (32%) and the least amount of grass (62%) while manure treatments resulted in the most bare ground (11%; P ≤ 0.05). The soil nutrients magnesium and phosphate were highest in compost-treated plots and nitrate-nitrogen and sodium were highest in manure-treated plots (P ≤ 0.05). Forage nutrient content did not differ across treatments (P > 0.05). Horses did not prefer pasture treated with manure and only 15 and 33% of forage was consumed after 2 and 4 h, respectively (P ≤ 0.001). All other treatments averaged 53 and 78% removal after 2 and 4 h, respectively. Based on differences observed in botanical composition and horse preference, commercial fertilizer and compost appear to be the most beneficial soil amendments for horse pastures.

Effects of plant-biochar interaction on the performance of a landfill cover system: field monitoring and numerical modelling

Biochar has been used as a sustainable amendment to moderate the risks of climate change to plant and soil management. A 3-year field monitoring was conducted at Shenzhen Xiaping landfill to evaluate the performance of a three-layer landfill cover using plant and biochar. Coarse-grained completely decomposed granites (CDG) amended with peanut shell biochar at 0%, 5% and 10% (m3/m3) were used for the top layers of three grass plots (10 m×5 m each), respectively. Coarse recycled concrete and fine-grained CDG were used for the middle and bottom layers of all plots. Numerical simulation was conducted to back analyse the monitored results. The results show that the grassed cover with biochar can retain over four times higher negative pore-water pressure than that without biochar. During the monitoring, over 62% of total rainfall was evapotranspirated from biochar amended covers, which was 10% larger than the cover without biochar. With biochar amendments, the infiltration amount was reduced by 13%, but water storage was improved by up to 15%. The measured and computed percolation of the grassed covers with 0%, 5% and 10% biochar meet the recommended criterion by USEPA. It is recommended that 5% biochar content is sufficient to minimise water percolation.

First Comprehensive Description of Salt Marsh Skipper (Panoquina panoquin) (Hesperiidae) Natural History: Confirmation of a Second Host Plant In Virginia Salt Marshes

In a rapidly changing world, a complete understanding of a butterfly species' natural history and information about each of the life stages from egg to adult is more important than ever. For many butterfly species, records on life history strategies and habitat requirements are often lacking, especially for immature stages. The salt marsh skipper (Panoquina panoquin) is one such example of an understudied species. As a specialist of salt marshes, studying these immature stages is important for understanding how this species interacts with and uses its habitat. The goal of this study was to fill in gaps in our knowledge of the natural history and habitat preferences of the salt marsh skipper. We conducted field surveys of ovipositing females in three Virginia coastal marshes (5 sites) between May and October 2021. In doing so, we characterized host plant use and oviposition microhabitat. We also tracked eggs and larvae to assess survival in relation to natal host plant. We observed the oviposition of 32 eggs, 15 of which were on Distichlis spicata and 17 on Spartina alterniflora. All life stages used S. alterniflora, including feeding by larvae, confirming this species as a novel host plant. S. alterniflora was the most abundant grass in egg plots and we found no difference between random and egg plot microhabitat. In the microhabitat analysis, we found that host plant use was largely associated with the more abundant of the two grasses in a plot. D. spicata, however, was preferred in cases of up to 26% more S. alterniflora cover relative to D. spicata. Lastly, we documented an overall successful hatching rate of 19% with equal risk of egg mortality on both host plants. While our results still indicate that the salt marsh skipper is a specialist, it has a broader range of habitat and might be able to cope with marsh decline better than previously thought.

Deep mowing rather than fire restrains grassland Miscanthus growth via affecting soil nutrient loss and microbial community redistribution.

Fire and mowing are crucial drivers of grass growth. However, their effects on soil properties, microbial communities, and plant productivity in dry-alkaline grasslands have not been well investigated. This study evaluated the effects of mowing (slightly and deeply) and fire on vegetation traits (Tiller number per cluster and plant height) and biomass (plant dry weight), and soil availability of N, P, and K, as well as soil microorganism abundance in a Miscanthus system. We designed one control and three experimental grass plots (slightly and deeply mowed, and burned) in 2020-2021 in the Xi'an Botanical Garden of Shaanxi Province, Xi'an, China. Tiller number, plant height per cluster, and soil N, P, and K availability during Miscanthus growth decreased significantly (p < 0.05) in all treatments compared to the control. However, this effect was much greater in the deep-mowing plot than in the other plots. After harvest, deep mowing induced the greatest effect on biomass among all treatments, as it induced a 5.2-fold decrease in dry biomass relative to the control. In addition, both fire and mowing slightly redistributed the community and diversity of the soil bacteria and fungi. This redistribution was significantly greater in the deep-mowing plot than in other plots. In particular, relative to the control, deep mowing increased the abundance of Firmicutes and especially Proteobacteria among soil bacterial communities, but significantly (p < 0.05) decreased Basidiomycota and increased Ascomycota abundance among soil fungal communities. We conclude that nutrient limitation (N, P, and K) is crucial for Miscanthus growth in both mowing and fire grasslands, whereas deep mowing can induce soil nutrient loss and microorganism redistribution, further restraining grass sustainability in dry-alkaline grasslands.

Response of soil moisture to vegetation and trade-off analysis in the hilly area of the Loess Plateau, China

It is said that in a synergistic relationship between vegetation and soil moisture (SM), the latter may be consumed excessively, while at the same time improving the ecological environment, such as in the large-scale artificial vegetation planting areas on the Loess Plateau. At present, the possibility of vegetation restoration and its impact on the water ecology of the Loess Plateau have received extensive attention. In this study, piecewise linear regression (PLR) and nonparametric conditional quantile regression (NCQR) models have been innovatively applied to vegetation survey data and soil moisture data from 50 field samples to explore the trade-off relationship between soil moisture and various vegetation parameters (VPs) and the response of soil moisture to the vegetation. The results showed that precipitation and topography are significantly linearly related to soil moisture in the sampling plots. Affected by irrational planting, the soil moisture benefit at 20–40 cm is significant weaker than that at 0–20 cm (plot 4, 5, 26 and 44). Some sampling plots excessively consumed soil water to promote vegetation planting. Although there was stronger soil water infiltration by shrubs, it was noted that the vegetation planting plan in some grass plots and shrub-grass plots were unreasonable and needed to be adjusted due to the clear risk of a soil water deficit determined by the trade-off values (represented by the root mean square deviation), plant species, a multiparameter evaluation. With the increase in soil moisture in the sampling plots, the negative correlation between the trade-off (soil moisture and vegetation) and soil moisture was transformed into a positive correlation (the inflection point was 8.5–10%). In addition, the benefit of soil moisture gradually changed from “shortage” to “appropriateness” and even “excess” (the inflection point was 15–20%). The fitting results of the two models are optimal and show clear applicability for evaluating trade-off relationships. Among the VPs involved in the calculation, the Shannon–Wiener index (H), Margarlef index (D1) and Fractional Vegetation Cover index (FVC) demonstrated better regional representation and stability.

Improvements in soil physical properties after long-term manure addition depend on soil and crop type

Manure application and crop rotation are common agricultural practices that can alter soil physical properties and affect soil functions. In this study, we assessed the effect of long-term manure fertilization (24 to 126 years) and crop type on soil hydraulic, aggregate and pore structural properties. Samples were collected from three long-term experiments (LTEs) in Sweden (silty clay, SiC), Germany (silt loam, SiL) and Denmark (sandy loam, SL). Measurements included water retention, air permeability and gas diffusivity measured at five matric potentials −3, −5, −10, −30 and −50 kPa, saturated hydraulic conductivity (Ksat), bulk density (ρb), and water-stable aggregates (WSA). The treatments at the three LTEs included various manure rates and crop sequences (winter wheat, maize, spring barley, and grass/clover). Results showed that long-term manure addition reduced ρb by an average of 3–6% for all three sites, and improved soil water retention, plant available water and WSA for most investigated plots. However, increasing manure rates for the SiL and SL sites did not result in further improvements in soil water retention, ρb and water-stable aggregates. The effect of manure on soil pore size distribution, gas transport, and Ksat varied with soil and crop type. Manure increased the porosity of pores < 30 µm in the two fine-textured sites and increased the porosity of pores > 30 µm for wheat and maize plots in the SL site. Manure improved gas transport and Ksat in the wheat plots and decreased these properties in the barley plots regardless of soil texture. The maize plots in the SL site had well developed pore structure, while the pore structure in the SiL site was relatively poor. Grass plots had poorer gas transport than maize plots in the SL site despite the manure addition. The study shows that improvements in soil physical and chemical properties arising from manure application largely depend on the crops grown and the soil texture.

Drawbar Performance of Tractor Tyres with Steel Spikes At 100%-Wheel Slip

Abstract A driving wheel is a part of a tractor, which transmits forces from a tyre to the ground. Therefore, it affects the tractor movement and the pulling of an implement. The paper is aimed at a tractive performance evaluation of special driving wheels based on drawbar pull at 100%-slip. These wheels consist of steel spikes to be applied in the base or working position. The design is characterized by the spikes placed in a tyre-tread pattern. The rubber lugs of the tyre are higher than spikes, therefore, they are not in contact with the ground in the base position. The spikes in the working position exceed the tyre diameter to be in contact with the ground. Tests were performed on a grass plot at a relatively low soil moisture. The spike tyres were compared with the standard tyres using a sub-compact tractor. An increase in drawbar pull reached a statistically significant value of 15.9% in the 2nd gear and 16.7% in the 1st gear.

Adding corn meal into mixed elephant grass–butterfly pea legume silages improves nutritive value and dry matter recovery

AbstractThe objective of this study was to describe and explain the effect of adding corn meal (CM) on losses, fermentation characteristics and nutritional value of silages from two elephant grass [Cenchrus purpureus (Schumach.) Morrone] genotypes (Taiwan A-146 2.37 and IRI-381) mixed with butterfly pea (Clitoria ternatea L.) legume. The forage was harvested at 75 days of regrowth from elephant grass plots intercropped with butterfly pea legume and ensiled with or without CM at 5% of dry matter (DM) content. Greater gas losses (12 g/kg) and pH (4.2) were observed in the Taiwan A-146 2.37 + butterfly pea silages. The greatest crude protein content was observed in the ‘Taiwan A-146 2.37’ + butterfly pea silage added with CM (116 g/kg). Silages with additive and those containing IRI-381 had a greater acid detergent fibre content (367 and 366 g/kg, respectively). CM increased the silage DM (221 g/kg), remaining water-soluble carbohydrates contents (26 g/kg) and in vitro digestibility of DM. The aerobic stability was maintained until 45 h after opening the silos. All silages presented a good fermentative profile and were not affected by the relatively large proportion of butterfly pea (&gt;34%) in the ensiled mass as indicated by the reduced contents of butyric acid and ammonia nitrogen. CM reduces total losses, increases DM recovery and improves the nutritional value of silages from mixed elephant grass–butterfly pea legume.

Dynamic algorithmic conversion of compressed sward height to dry matter yield by a rising plate meter

The strategic allocation of pasture grazing area to dairy cows is essential for optimal management and increased outputs. Rising plate meters are frequently used to estimate pasture herbage mass, i.e. dry matter yield per hectare, by employing simple regression equations that relate compressed sward height to herbage mass. However, to improve the accuracy and precision of these equations, so that inherent variation of grasslands is captured, there is a need to incorporate differences in grass types and seasonal growth. Using a total of 308 grass plots, the variation of growth for both perennial ryegrass and hybrid ryegrass was recorded over the seven-month growing season, i.e. March–September. From these data three dynamic equations were derived. The models showed reduced levels of error in comparison to most other conventional equations. As such, the derived models represent a considerable advance for predictive assessment of herbage mass and will support more efficient grassland utilisation by farmers. Although all equations were found to be highly accurate and precise, only a single equation was considered the most effective (R2 = 0.7; RMSE = 248.05), allowing herbage mass to be predicted reliably from compressed sward height data in relation to ryegrass type and calendar month. Although further research will be required, the results presented allow farm operators to calculate herbage mass, as well as support the development of decision support tools to improve on-farm grassland management, particularly at the local paddock rather than national level.

Soil pH-increase strongly mitigated N2O emissions following ploughing of grass and clover swards in autumn: A winter field study

Emissions from crop residues contribute largely to the total estimated N2O emissions from agriculture. Since low soil pH increases N2O production by impairing the last denitrification step, liming has been suggested as a mitigation strategy; however, it may also increase N2O emissions by enhancing mineralization and nitrification. To gain field-based empirical knowledge, we measured N2O fluxes with an autonomous field-flux robot in limed and control plots before and after autumn ploughing of 3-year-old grass, clover grass or red clover swards under different N fertilization regimes. Dolomite applied before establishing the swards raised soil pHCaCl2 from ~4.8 to ~5.8 in limed plots.Higher pH halved emissions from ploughed leys despite higher soil mineral N contents. It also reduced emissions before ploughing. We observed substantial N2O fluxes after ploughing, with peaks during a relatively warm wet period after freezing and higher peaks during diurnal snow melt over frozen soil. Average N2O fluxes were strongly positively correlated with high herbage yields in the preceding growing seasons rather than with the presence of clover. The yield-scaled average N2O fluxes were strongest in low pH soils at all yield levels; this was a true effect of soil pH on N2O, as herbage yields were not increased by liming. Here, yield-scaled flux was defined as the average N2O flux after ploughing divided by the dry matter. Fluxes in red clover plots were similar to those in grass plots, despite the lower C/N ratio and higher total amount of N in clover residues. However, clover in mixtures with grass increased yields and N2O emissions. This suggests that higher ley production enhanced microbial activity, including nitrifiers and denitrifiers, and that the pH effect on facilitating complete denitrification to N2 overrode any effect on mineralization and nitrification, thus resulting in N2O mitigation.

Characteristics of Plant Diversity and Heavy Metal Enrichment and Migration Under Different Ecological Restoration Modes in Abandoned Mining Areas

In order to select plant materials suitable for the ecological restoration of abandoned mining land, ecological restoration experiments were set up in landfills. The effects of different ecological restoration measures on plant diversity and heavy metal enrichment and migration characteristics were studied. The results showed that under different ecological restoration measures, a total of eight families and 10 species of surviving plants appeared, most of which were herbs. The restoration effect of the arbor shrub and grass plots was the best; the plant coverage reached 100%, and the survival rate was over 69%. The diversity index of the plant community was as follows:arbor shrub grass > shrub grass > joe grass > grass. The dominant plants under different ecological restoration measures were Pinus elliottii, Ligustrum lucidum, Boehmeria nivea, Lagerstroemia indica, and Plantago asiatica. The contents of most heavy metals in plants were higher than the normal values. Among them, the enrichment and transfer coefficients of the leaf stems of P. elliottii and L. indica were close to or greater than 1, showing a strong ability of enrichment and transfer to Cd; these two plants belong to Cd-enrichment type plants. The roots of L. lucidum Ait and P. asiatica, which are root-hoarding plants, had a high retention rate of heavy metals. Boehmeria nivea was a heavy metal-avoidance plant with a low content of heavy metals in each part and had the ability to fix and repair potential soil heavy metal pollution. Considering the diversity of plants and the ability of plant enrichment and migration, the combination of trees, shrubs, and grasses was the best restoration mode. Pinus elliottii, L. indica, and P. asiatica can be the target plants for ecological restoration in the abandoned land of mining areas.