Perennial Pasture Research Articles

Pasture Recovery Period Affects Humic Substances and Oxidations of Organic Matter in Eastern Amazon

Land management practices that overlook soil limitations and potential have led to varying degrees of degradation. This study evaluates the carbon content in chemical and oxidisable soil fractions across different pasture recovery periods, comparing them to secondary forests. The management practices assessed include the following: secondary forest (SF), perennial pasture (PP), perennial pasture recovered five years ago (P5), and perennial pasture recovered eight years ago (P8), all on Plinthosols. We analysed carbon levels in oxidisable fractions and humic substances at depths of 0–0.10 m, 0.10–0.20 m, 0.20–0.30 m, and 0.30–0.40 m. The SF and P8 areas showed the highest organic matter content within the humic fractions, compared to the PP and P5 areas. Additionally, the P8 area demonstrated an increase in the labile and moderately recalcitrant fractions of organic matter, standing out among the different fractions evaluated. The multivariate principal component analysis indicated that P8 has the greatest impact on soil quality, followed by FS, P5, and PP. The pasture recovery over the past eight years has significantly improved soil carbon accumulation, highlighting the benefits of land restoration.

Nutrient transformations based on sampling scheme and cropping system following subsurface‐banded poultry litter

AbstractPoultry litter (PL) is an excellent source of micro‐ and macronutrients. However, surface applications result in greater nutrient runoff and nitrogen loss via ammonia volatilization. Subsurface banding PL is a promising technology for combating these challenges, but scant information exists on proper soil sampling techniques and management recommendations for subsurface‐applied PL. Therefore, objectives were to quantify the nutrient status based on sampling depth (0–15 cm and 15–30 cm) and schema (systematic [0, 3, 7, and 10 cm from PL bands] and composite) to develop subsurface PL recommendations per system (annual cropping and perennial pasture). Soil samples were collected during PL application (subsurface and surface) and 1, 6, 12, 18, and 24 months thereafter. On average, total N, Mehlich‐3 extractable P, and Mehlich‐3 extractable K were 15%, 96%, and 72% greater, respectively, for subsurface compared to surface applications. Further, Mehlich‐3 and water‐soluble P at the 0‐ to 15‐cm depth were 4–5 and 2–3 times greater in soils receiving subsurface PL in perennial pasture and row crop systems, respectively, compared to surface applications, likely owing to lesser nutrient losses to the air, soil, and water under subsurface PL systems. Compared to surface applications, subsurface PL increased (p < 0.05) N, P, and K crop removal by 75%, 70%, and 72%, respectively, and resulted in 80% and 78% yield increases and N‐use efficiency, respectively. Consequently, subsurface PL conserved greater N, P, and K at the 0‐ to 15‐cm depth, thus increasing nutrient‐use efficiency in row crop systems and improving water quality in sensitive watersheds.

Improving an agroforestry system with livestock in southern Brazil

Agroforestry systems hold significant environmental and cultural value but are yet to receive economic valorisation. In southern Brazil there is a centuries old agroforestry system called Caíva which is classified as a silvopastoral system, combining native trees, cattle herds and pastures. Caívas occupy significant land area and contribute to priceless forest conservation, maintaining rare and threatened trees, but challenges of legal insecurity, low economic yield and ineffective management are threatening the preservation of caívas. To address these challenges, the Agricultural Research and Rural Extension Company of Santa Catarina State (Epagri) began conducting research in 2006 to develop technologies that would increase productivity while maintaining forest cover. Their technology has shown promising results, increasing animal production by up to 400% while still maintaining the tree stratum and active forest regeneration. Epagri’s technologies are based on five activities: the selection of adapted perennial pastures, planting improved pastures without soil disturbance, soil liming and annual fertilisation, rotational grazing, and overseeding with ryegrass and clover during the autumn/winter period. By adopting Epagri's technologies, caíva owners can increase their income, maintain active forest regeneration, and ensure legal certainty over their properties. These strategies are primarily applicable to open and very open caívas, and it is recommended that other types of caívas be used for the preservation and provision of ecosystem services. Research on caivas improvement has shown multiple benefits, emphasising the importance of continued investment in research and development, to further valorise agroforestry systems. It is essential, however, to balance these productive improvements with the maintenance of permanent preservation areas and mixed ombrophilous forest landscapes.

Long-term liming changes pasture mineral profile

There is limited information on changes of pasture mineral concentrations over the long-term in response to liming. A long-term field experiment was conducted to assess the influence of lime application on (a) changes in pasture mineral composition over time; and (b) key pasture mineral concentrations and ratios important to animal health. Perennial and annual pastures with or without lime application were sampled annually over 12 years and analysed for macro- and micro-minerals. Mineral ratios and indices were calculated to assess the potential impact on animal health. Liming increased the concentrations of calcium, sodium and silicon, but decreased the concentrations of micro-nutrients including copper, zinc and manganese. The same trend was found in both annual and perennial pastures although there were some fluctuations between years. Liming increased the calcium:phosphorus ratio and the dietary cation–anion difference but reduced the tetany index on both annual and perennial pastures. These findings suggest a potential benefit to improve animal health outcomes for some disorders on the limed pastures. However, the reduced concentrations of some trace elements following liming potentially decreases antioxidant capacity and requires further research.

Soil health and root‐zone enrichment characteristics between paired grassland and cropland fields in the southeastern United States

AbstractBackgroundSoil organic C and N data from privately managed pastures in the southeastern United States are relatively scant.MethodsA paired‐farm approach was deployed to determine how a variety of soil health parameters related to nutrient and water cycling might be altered under grazed, botanically diverse perennial pastures compared with annual monoculture croplands in three Major Land Resource Areas of the southeastern United States.ResultsSoil stability index averaged 0.64 and 0.91 mm mm−1 under cropland and grazed pasture, respectively, suggesting that pastures had a more stable soil surface that was resistant to erosion and allowed rapid water infiltration. Surface‐soil organic C and N fractions (i.e., total, particulate, and mineralizable fractions at 0–10 cm depth) were greater under pasture than under cropland. Across locations, root‐zone enrichments (0–30 cm depth) of organic C and N fractions were greater under pasture than under cropland. Within locations, root‐zone enrichment of total soil N was greater (p < 0.05) under pasture than under cropland in the Blue Ridge (2.87 vs. 1.10 Mg N ha−1, respectively) and the Piedmont (2.80 vs. 2.10 Mg N ha−1), but not in the Blackland Prairie (2.40 vs. 2.12 Mg N ha−1).ConclusionsThis study provides evidence that rotationally grazed, perennial grasslands can store more soil organic C and N and improve soil surface stability conditions compared with neighboring croplands producing commodity feed grains for feedlot finishing.

156 Winter Hardy Cereal Cover Crops for Spring Grazing in Nebraska

Abstract Soybean harvest leaves little residue, potentially subjecting the soil to negative environmental impacts. Additionally, integrated livestock producers with crops and cattle identified a need to fill early spring forage deficiencies. Planting winter-hardy cereal cover crops after soybean harvest provides ground cover until the next cash crop is planted and has potential for early spring grazing before perennial pastures are ready. A 3-year study was conducted near Mead, Nebraska to evaluate the grazing potential of winter wheat, winter triticale, and cereal rye when planted after soybean harvest. A 7.3-ha field was split into nine 0.81-h paddocks and paddocks were then randomly assigned to a small cereal species (n = 3 paddocks per treatment), then divided further into 2, 0.4 ha paddocks to allow for rotational grazing within the assigned paddock. Growing steers were stratified by body weight (BW) and randomly assigned to paddock with 6 steers per paddock in years 1 and 2, and 5 steers per paddock in year 3. Steers were limit-fed at 2% of BW to equalize gut fill and weighed before and at the conclusion of grazing. Grazing was initiated when a paddock reached 13 cm. The initial BW did not differ among treatments (P > 0.05) with steers weighing 303, 335, and 372 kg in years 1 through 3, respectively. The final BW did not differ among treatments (P > 0.05). There was a treatment by year interaction (P ≤ 0.01) for average daily gain (ADG). There were no differences (P > 0.05) in ADG among treatments in year 1 (1.9 kg/d) or year 3 (1.3 kg/d). However, in year 2, steers grazing rye gained more (P < 0.01) at 1.4 kg than wheat (0.83 kg) and triticale (0.67 kg), which did not differ (P > 0.05). There were no differences (P > 0.05) among treatments for animal unit months (AUM) per hectare. Year 1 provided the most (P < 0.01) grazing at 5.1 AUM/ha, year 2 provided the least (P < 0.01) at 2.4 AUM/ha, and year 3 was intermediate at 3.1 AUM/ha. For gain per hectare (GPH), there were no differences (P > 0.05) among treatments. Steers in year 1 had greater (P < 0.01) GPH (390 kg/ha) than subsequent years, with year 2 (93 kg/ha) being less (P < 0.01) than year 3 (151 kg/ha). For all 3 years, there were no differences among treatments in pre-graze (P > 0.05) or post-graze biomass (P > 0.05). These data suggest that during early spring there are no major differences in the grazing potential and growing cattle performance for wheat, rye, or triticale in eastern Nebraska.

Seedling emergence of tropical perennial pasture species in response to temperature used to determine sowing time recommendations

Tropical pasture grasses and legumes can be highly productive and persistent and fill the summer-autumn feed gap typical of temperate pasture systems in southern Australia. However, more information is needed on optimum temperature range for seedling emergence because this will influence sowing time recommendations. A replicated field experiment was conducted at 5 locations in New South Wales over a 12-month period to determine the optimum temperature for emergence of a range of tropical species: Rhodes grass (Chloris gayana Kunth), Makarikari grass (Panicum coloratum L. var. makarikariense Gooss.), kikuyu grass (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone), digit grass (Digitaria eriantha Steud.), panic grass (Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs), paspalum (Paspalum dilatatum Poir.), Urochloa hybrid (Urochloa decumbens × U. ruziziensis × U. brizantha), 2 cultivars of Desmanthus virgatus (L.) Willd. (cultivars ‘Marc’ and ‘JCU2’), D. bicornutus (S. Watson), D. leptophyllus (Kunth) and D. pernambucanus (L.) Thell.). Rhodes grass emerged satisfactorily over the longest time across all sites, exhibiting the greatest temperature range over which emergence occurred, while Makarikari grass and panic grass had the narrowest temperature range for emergence. The temperature for 50% emergence differed between the tropical species and whether the soils were warming or cooling. Rhodes grass had the lowest 50% emergence temperature (17 °C) while paspalum had the highest (22 °C). Results showed that temperature for 50% emergence is a useful indicator for determining sowing time in warming soils.

Management impacts on organic carbon under continuous perennial grass, perennial grass-legume mixture, and annual cereals on a thick Black Chernozemic soil

Impacts of annual and perennial pasture management on soil organic carbon (SOC) and equivalent SOC stocks (equal soil mass basis) were investigated in two trials [CAESA (1994–1997) and BMP (2008–2012) trials] conducted on the same experimental paddocks at Lacombe, AB. The original site was broken from perennial grass in 1992, and the CAESA trial established in 1993. Between 1994 and 1997, half of the paddocks included winter triticale and a mixture of triticale and spring barley; half included smooth and meadow bromegrass; and each paddock was light, medium, or heavily grazed. The BMP trial (2008–2012) on the same paddocks included fertilized, direct seeded barley as silage; grazing and haying of unfertilized meadow bromegrass, fertilized meadow bromegrass, and meadow bromegrass and alfalfa mixture; and unfertilized oldgrass that was continuous since 1994. Between trials (1998–2007), all paddocks received no fertilizer. In the 0–15 cm depth, SOC under oldgrass was constant between 1994 and 2012 and averaged 88 Mg C ha−1. Under barley silage, SOC decreased from 89 to 72 Mg C ha−1 by 2012. Between 1994 and 2012, SOC decreased in all treatments re-established on original annual forage (1994–1998) but not to the level of barley silage. Light fraction carbon was the highest under oldgrass and the lowest under barley silage. Overall, oldgrass with no fertilizer inputs maintained a constant SOC, although annuals reduced SOC stocks. Re-establishment of perennial grass with grazing may therefore reduce SOC loss, whereas haying perennial grass may not reduce SOC loss.

Carbon, nitrogen, and physical fractions of organic matter in recovered pastures of the Maranhense Amazon

In Maranhão State, Brazil, soils are naturally acidic, nutrient-deficient, and prone to cohesion and erosion. Removing the natural cover to establish pastures causes physical, chemical, and biological changes in the soil. Therefore, this study aimed to evaluate the contents and stocks of carbon (C), nitrogen (N), and particle-size fractions of soil organic matter (SOM) in pastures with different years of recovery, and compare them with a secondary forest in the Legal Amazon. Four treatments were evaluated: secondary forest, perennial pasture, and perennial pastures recovered for five years and eight years, both of the latter through corn + brachiaria intercropping. The contents and stocks of total organic carbon, total nitrogen, C, and N from the soil organic matter particle-size fractions, as well as the carbon management indexes (CMI) of the 0.00–0.10, 0.10–0.20, 0.20–0.30, and 0.30–0.40 m layers were evaluated. The perennial pasture environment presented the highest total soil C and N contents; however, when observing the granulometric fractions and CMI, these increases were qualitative in relation to the secondary forest. Pasture recovery over eight years contributed to an improvement of soil quality similar to secondary forest, indicating that an increase in SOM quality, quantity, and recovery time related to increased pasture capacity to accumulate C and N in the soil.

Species and functional diversity of cool-season pastures are influenced by warm-season grazing management

CONTEXTIn southern Brazil, livestock producers often overseed cool-season annual grasses into warm-season perennial pastures to extend the grazing season and improve animal performance. However, the effects of warm-season pasture management on the subsequent cool-season pasture are poorly understood. OBJECTIVEWe aimed to evaluate how grazing height and nitrogen (N) fertilization applied to a mixed-species pasture during the warm season affect forage accumulation and diversity in the cool-season pastures. METHODSThe experiment was conducted in a subtropical climate and consisted of two phases: warm season (November/December – April/May) and cool season (May – October/November). During the warm season, we applied a factorial combination of two pre-grazing heights (0.17 and 0.23 m) and three N rates (50, 150, and 250 kg N ha−1) to a mixed-species pasture. During the cool season, we managed all plots equally and measured forage accumulation and diversity using Simpson's and Rao's indices. RESULTS AND CONCLUSIONSWe found that warm-season N fertilization had no residual effect on cool-season pasture responses, but grazing at 0.17 m height during the warm season resulted in higher forage accumulation during the cool season than grazing at 0.23 m height (5100 vs. 4780 kg DM ha−1). However, grazing at 0.23 m height during the warm season increased species diversity (Simpson's index of 0.49 vs. 0.40) and functional diversity (Rao's index of 0.33 vs. 0.29) during the cool season compared to grazing at 0.17 m height. SIGNIFICANCEThis study provides novel insights into the long-term effects of warm-season pasture management on cool-season pasture diversity and productivity in a subtropical climate. It shows that grazing at a height close to the critical leaf area index during the warm season can increase legume proportion and functional diversity in the cool season, which can improve pasture resilience and sustainability. While this study offers valuable insights, it is important to acknowledge its restriction to a single location, and the need to assess the hypothesis raised here to other sites and conditions.

Diversity of early flowering plants of the Ulytau mountains (Central Kazakhstan)

Early flowering plants (ephemers and ephemeroids) are an important component of the biosystem of steppes and deserts. These species form perennial pasture communities, for early grazing. The present work was conducted to evaluate the floristic checklist and ecological uniqueness of early flowering plants of Central Kazakhstan, in the forest-steppe regions of Em-Bulak region and Edige mountains, during 2021 and 2022. A total of 26 species of ephemers and ephemeroids were recorded, which belong to 16 families: Liliaceae – 3 species, Asteraceae – 3 species, Ranunculaceae – 3 species, Rosaceae – 3 species, Brassicaceae – 2 species, Boraginaceae – 2 species, the other families are represented by one species. According to ecomorphological characteristics: 8 species (31%) belong to the xerophyte group, 6 (23%) to the xeromesophyte group, 7 (27%) to the mesoxerophyte group and 5 (19%) to the mesophyte group. Also, as a result of our research we found two species of plants which are included in the Red Book of the Republic of Kazakhstan – Pulsatilla patens (L.) Mill. and Tulipa patens Agardh. ex Schult. f. The data obtained can be used for environmental monitoring and issues of rational nature management of wild plants of Central Kazakhstan.

Short-Term Impact of Recycling-Derived Fertilizers on Their P Supply for Perennial Ryegrass (Lolium perenne).

Various nutrient recycling technologies are currently under development in order to alleviate the dependency of non-renewable raw material for the production of mineral phosphorus fertilizers commonly used in agriculture. The resulting products, such as struvites and ashes, need to be assessed for their application as so-called recycling-derived fertilizers (RDFs) in the agricultural sector prior to commercialization. Here, we conducted a short-term (54 days) trial to investigate the impact of different phosphorus fertilizers on plant growth and the soil P cycling microbiota. Lolium perenne was grown with application of superphosphate (SP) as inorganic fertilizer, two ashes (poultry litter ash (PLA) and sewage sludge ash (SSA)), and two struvites (municipal wastewater struvite (MWS) and commercial CrystalGreen® (CGS)) applied at 20 and 60 kg P ha-1 in four replicates. A P-free control (SP0) was also included in the trial. Struvite application increased plant dry weights, and available P acid phosphatase activity was significantly improved for struvites at the high P application rate. The ash RDFs showed a liming effect at 60 kg P ha-1, and PLA60 negatively affected acid phosphatase activity, while PLA20 had significantly lower phoD copy numbers. P mobilization from phosphonates and phytates was not affected. TCP solubilization was negatively affected by mineral SP fertilizer application at both P concentrations. The bacterial (16S and phoD) communities were only marginally affected by the tested P fertilizers. Overall, struvites appeared to be a suitable substitute for superphosphate fertilization for Irish L. perenne pastures.

Responses of Deep Soil Carbon and Nitrogen Contents to Long-Term Retention of Alfalfa Pasture on Infertile Loess: A Synthesis Study

Incorporating perennial pastures into annual crop systems is an efficient means of improving soil carbon (C) sequestration and reducing the application of nitrogen (N) fertilizer on farmlands. How the soil C and N at different soil depths respond to the length of pasture duration and rainfall conditions is still being determined. In this study, we conducted a meta-analysis of data from 63 published studies to investigate the impacts of the alfalfa pasture on the incorporation of soil organic carbon (SOC), total nitrogen (STN), and available nitrogen (SAN) contents in the 0–300 cm soil profile of the Loess Plateau. An annual crop field was taken as a reference. The results showed that the average SOC content at soil depths of 0–100 and 100–200 cm in the alfalfa pasture increased by 17% and 8% (p < 0.001) compared to the crop field, respectively, while that at 200–300 cm decreased (p > 0.05). The SOC content increased with pasture age; it was the highest when the alfalfa had been planted for 5–9 years and decreased thereafter. The STN content at soil depths of 0–100 and 100–200 cm increased by 19% and 14% (p < 0.001), respectively; the content at depths of 200–300 cm only increased slightly (p > 0.05). It also increased the most when the alfalfa was 5–9 years old. The increments in the SAN content at the 0–100 and 100–200 cm soil depths were higher than those of the STN, with values of 29% and 18%, respectively, while those at depths of 200–300 cm also changed insignificantly (p > 0.05). The SAN content continuously increased with the age of the alfalfa, and the average increment in the 0–300 cm profile was as high as 21% when the alfalfa was ≥10 years old. The SOC and STN content increased the most under moderate rainfall conditions (350–500 mm), while the SAN content maintained the highest increment under high rainfall (500–650 mm) conditions. Therefore, ley farming with the alfalfa pasture contributed substantially to the soil C and N at depths of 200 cm in deep loess. Alfalfa should be removed in its middle ages to increase C sequestration while utilizing soil N efficiently.

Paddock-scale carbon and greenhouse gas budgets in the first year following the renewal of an intensively grazed perennial pasture

Pasture renewal is an important tool commonly used by land managers to maintain a healthy productive pasture sward that can be used for grazing by animals or harvesting. However, there have been few assessments of the impact of pasture renewal on greenhouse gas (GHG) emissions, particularly in grazed pastures. We investigated how pasture renewal impacted the carbon (C), nitrous oxide (N2O) and GHG budgets of an intensively managed rotationally grazed New Zealand pasture by comparing adjacent paddocks with one undergoing pasture renewal. The eddy covariance technique was used to measure carbon dioxide (CO2), N2O and methane (CH4) fluxes which were coupled to measurements and estimates of non-gaseous C flows to calculate the net ecosystem carbon balance and total GHG budget. We measured GHG emissions directly due to pasture renewal of 695 g CO2-eq m-2 during the 66 days between herbicide application and the first grazing of the new pasture sward. Using an adjacent paddock as a control, the net effect of pasture renewal was 358 g CO2-eq m-2, primarily due to an additional grazing event in the non-renewed pasture and the associated CO2 and CH4 emissions associated with digestion of the pasture by the ruminant animals. The pasture renewal emissions were primarily due to C loss with increased N2O emissions accounting for only 10% of total GHG emissions during the renewal period. Total GHG emissions were 2017 g CO2-eq m-2 y-1 for the first year (before pasture renewal), and 1452 and 1894 g CO2-eq m-2 y-1 for the non-renewed and renewed pastures, respectively, in the second (renewal) year. The only significant difference was between the first year and the non-renewed pasture in the second year. We concluded that pasture renewal increased C loss, N2O emissions and total GHG emissions during the renewal period, but when extended to the annual timescale, the effect was insignificant compared to interannual variability.

Methane emissions and growth performance of beef cattle grazing multi-species swards in different pesticide-free integrated crop-livestock systems in southern Brazil

The aim of this study was to assess the growth performance, forage intake and methane (CH4) emissions by beef cattle grazing under different spatiotemporal integrated crop-livestock systems (ICLSs). The experiment was conducted for two years (2017–2018 and 2018–2019) in warm season perennial pastures and cool season annual pastures grazed by beef steers. Three pesticide-free ICLS treatments – livestock-forestry (LF); crop-livestock (CL), and crop-livestock-forestry (CLF) – plus, a livestock control pesticide-free system (L) were conducted in randomized complete block design, with three replicates per treatment. Maize crop rotation was done with cool season cover crop under no-tillage. Eucalyptus trees (Eucalyptus benthamii) were planted in 2013 and intercropped with tree alleys. The animal performance, organic matter (OM) intake and enteric CH4 emission, yield, and intensity were assessed. We found no significant difference (P > 0.05) for average daily gain (ADG), stocking rate (SR), and daily live weight gain (LWG) per area for the different ICLS arrangements and seasons. The ICLS arrangements did not affect (P > 0.05) CH4 emission, yield, and intensity, with averages of 186 g steer−1 day−1, 26 g kg−1 OM intake and 210 g kg−1 of ADG, respectively. The average CH4 emissions per steer per day, per OM intake, per ADG and LWG per area were greater (P < 0.05) for steers when grazing warm season compared to cool season pastures. The integration or not of beef cattle with crops and/or forestry does not influence CH4 emissions, yield, and intensity by beef steers grazing pastures under moderate grazing intensity. Our results reinforce that well-managed integrated systems are a reliable climate-smart agriculture alternative for increasing production, e.g., grain, wood, meat, and mitigating or without increasing greenhouse gas emissions, such as CH4 from enteric fermentation in beef cattle.

111 Forage Mass and Nutritive Value of Cool-Season Grass-Legume Mixtures Overseeded into Bahiagrass Pastures

Abstract Warm-season perennial pastures are the base of livestock production systems in lower Alabama. To overcome the shortage in forage production during the late fall and winter months, during bahiagrass dormancy, overseeding pastures with cool-season annuals can be used as an option for providing forage during this period. Diverse forage mixtures of multiple species and functional groups have gained popularity in use among forage-livestock producers, but few evaluations have been conducted in overseeded sods. The objective of the study was to evaluate forage mass and nutritive value of cool-season forage mixtures overseeded into bahiagrass pastures. Six, 0.40-ha paddocks of ‘Pensacola’ bahiagrass were overseeded with one of three cool-season forage mixtures (n = 2 paddocks/treatment) on November2, 2021: 1) oat (Avena sativa), wheat (Triticum aestivum), and balansa (Trifolium michelianum), red (Trifolium pratense), and white clover (Trifolium repens; ‘clovers’); 2) oat, cereal rye (Secale cereale), and clovers; and 3) cereal rye, annual ryegrass (Lolium multiflorum), and clovers. When forage mixtures reached a target grazing height of 20 cm, paddocks were managed using flash mob stocking with beef cow-calf pairs to graze to a target height of0 cm. Herbage mass, nutritive value, botanical composition and height samples were collected pre- and post-grazing events. There was no treatment (P = 0.240) or treatment × harvest (P = 0.4239) effect on forage mass. Harvest date affected (P = 0.029) forage mass, with greater forage mass at late harvest (1,903.33 kg DM·ha-1) than at early (1,253.33 kg DM·ha-1) in the growing season. There were no treatment effects observed for species components (P &amp;gt; 0.05), although grasses dominated the forage mixtures with an average of 80% grass presence. Legume establishment was poor (less than%) and the remaining species composition consisted of weed species (19%). There was a treatment effect (P = 0.003) on CP, where oat-rye-clovers had the greatest CP and rye-ryegrass-clover had the least CP. Oat-wheat-clover mixtures had greater TDN (79.2%), less NDF (39.8%), and ADF (18.7%) than cereal rye-ryegrass-clover (75.4%, 46.1%, and 22.2% for TDN, NDF, and ADF, respectively), but did not differ from oat-cereal rye-clover mixtures (76.6%, 45.7%, 21.0% for TDN, NDF, and ADF, respectively). In year of this study, overseeding bahiagrass supported forage production over a 2-month period and can be a management tool used to reduce the need for supplementing in the dormancy periods of warm season perennial grasses.

Active plant biomass inputs influence pore system functioning in no-till soils

Available knowledge about the exact impact of plant growth on the properties and functioning of no-till soils is somewhat limited, especially in tropical and subtropical regions. The starting hypothesis for this work was that long-term active plant biomass Input-APBI (aboveground plant shoot biomass) would improve pore system functioning in surface and subsurface soil layers by playing different, complementary roles in a previously degraded subtropical Acrisol. The hypothesis was checked by examining the results of a 34-yr field experiment involving five different cropping systems, namely: bare soil (BS), perennial pasture (PAST), oat/maize (O/M), oat + vetch/maize (O + V/M) and oat + vetch/ maize + cowpea (O + V/M + C). The soil was supplied with APBIs varying from 0.13 to 1.48 kg dry matter ha−1 yr−1. The APBIs for each cropping system were very low (BS), low (O/M), medium (O + V/M), high (O + V/M + C), and very high (PAST). The surface (0–5 cm) and subsurface (5–15 cm) soil layer were analyzed for static and dynamic properties of the pore system including bulk density; total, macro, and microporosity; the ability of the system to conduct air and water; continuity in soil pores; and plant-available water capacity. Micromorphological images of the soil revealed a complex pore network whose structure and functioning were both improved by the action of plants. In the surface soil layer, very high APBIs from pasture and high inputs from O + V/M + C increased total porosity by 11 and 14 %, respectively; pore continuity (Ncont) by 11 and 40 %, respectively; and microporosity by 31 and 23 %, respectively —all relative to bare soil. In the subsurface soil layer, pasture, and O + V/M + C decreased Ncont by 44 and 40 %, respectively, but increased water permeability (kw) by a factor of 6.5 and 7, respectively. In addition, very high APBIs increased continuity and permeability to air in macropores relative to BS. Organized large macropores in the subsurface soil layer efficiently conducted water and air from the soil surface and acted as bridges between the surface and subsurface soil layer. Overall, our findings suggest that APBIs helped develop a pore system with differential properties and complementary functions that influenced water infiltration and air fluxes in the surface soil layer, and water availability to crops in the subsurface soil layer, through long-term self-organization in the system. Future research with a view to understanding the influence of species richness and roots on physical quality in no-till soils is recommended.

Natural grassland conversion to cultivated pastures increases soil microbial niche specialization with consequences for ecological processes

The conversion of natural grasslands to cultivated pastures has a profound effect on the soil habitat conditions, influencing the proportion of soil specialist and generalist microbes, with consequences for the assembly of microbial communities. This often leads to the homogenization of the microbial community and thus favoring stochastic assembly processes. However, there is still a gap in understanding the effect of conversion from natural grasslands to cultivated pastures on soil microbial ecological processes. Therefore, we aimed to investigate the assembly patterns of microbial communities and evaluate the ecological models for generalists and specialist microbes along a grassland management intensification gradient. Through 16S rRNA amplicon sequencing, we found that the conversion of natural grasslands to cultivated pastures has increased the number of microbial specialists, resulting in stochastic assembly processes due to the decrease in plant diversity. Moreover, the ecological processes governing the assembly of microbial communities were affected by soil and vegetation management. The perennial pasture was more affected by homogenizing selection, owing to the lower plant diversity and uniform plant covering and root development. We have found that the generalists in the grasslands are shaped by niche-based models, while the specialists in natural grasslands are more stochastic in nature. For improved pastures, we have found that lognormal and preemption models are more predominant, suggesting that homogenizing dispersal is more predominant than variable selection. We highlight it is essential to comprehend these assembly models and ecological processes to ensure plant-microbe supporting and provisioning ecosystem services for cattle, and humans while establishing management strategies and conservation policy priorities.

Effect of Long-Term Semiarid Pasture Management on Soil Hydraulic and Thermal Properties

Semiarid pasture management strategies can affect soil hydraulic and thermal properties that determine water fluxes and storage, and heat flow in unsaturated soils. We evaluated long-term (>10 years) perennial and annual semiarid pasture system effects on saturated hydraulic conductivity (ks), soil water retention curves (SWRCs), soil water thresholds (i.e., volumetric water content (θv) at saturation, field capacity (FC), and permanent wilting point (PWP); plant available water (PAW)), thermal conductivity (λ), and diffusivity (Dt) within the 0-20 cm soil depth. Forage systems included: Old World bluestem (Bothriochloa bladhii) + legumes (predominantly alfalfa (Medicago sativa)) (OWB-legume), native grass-mix (native), alfalfa + tall wheatgrass (Thinopyrum ponticum) (alfalfa-TW), and annual grass-mix (annual) pastures on a clay loam soil; and native, teff (Eragrostis tef), OWB-grazed, and OWB-ungrazed pastures on a sandy clay loam soil. The perennial OWB-legume and native pastures had increased soil organic matter (SOM) and reduced bulk density (ρb), improving ks, soil water thresholds, λ, and Dt, compared to annual teff and alfalfa-TW (P < 0.05). Soil λ, but not Dt, increased with increasing θv. Grazed pastures decreased ks and water retention compared to other treatments (P < 0.05), yet did not affect λ and Dt (P > 0.05), likely due to higher ρb and contact between particles. Greater λ and Dt at saturation and PWP in perennial versus annual pastures may be attributed to differing SOM and ρb, and some a priori differences in soil texture. Overall, our results suggest that perennial pasture systems are more beneficial than annual systems for soil water storage and heat movement in semiarid regions.

Chemical, physical, and biological properties of soil with pastures recovered by integration crop-livestock system in Eastern Amazon

Soil quality can be understood as its capacity to provide several essential services within the ecosystem and has been used to understand the impact of different managements, providing information that proves the benefits and your maintenance of the agroecosystem. To understand the impact of different managements, this study aimed to compare the chemical, physical, and biological soil properties in pasture areas managed with different recovery times in an integrated crop-livestock system about perennial pastures and secondary forest. The following [...]