Grasses

Understanding greenhouse gas (GHG) emissions from turfgrass allows managers to make cultural management decisions to reduce GHG emissions. The objective of this study was to evaluate fertilizer source [urea (URE), polymer-encapsulated urea (POL), and milorganite (MIL)] and site location (green, wet rough, and dry rough) on GHG [carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)] emissions. Greenhouse gas data, soil temperature, soil moisture, canopy greenness, and turfgrass quality were collected. High soil temperature and moisture were correlated with soil CO₂ and N₂O flux. The wet rough fluxed more soil CH₄ across the 2-year study. The POL fluxed the highest amount of soil CO₂, while POL and MIL fluxed the largest amount of soil N₂O on the wet rough. Milorganite and POL increased canopy greenness in both roughs during the spring. On the green, URE produced greater canopy greenness in the spring and fall. Our results indicate that when soil moisture and temperature are high, turfgrass managers should employ methods of reducing soil temperatures that do not increase soil moisture to reduce GHG emissions. Under warm and wet conditions, gaseous losses of GHGs are accelerated with slow-release fertilizers. Full article

The objective of this study was to evaluate the characteristics and recovery of minerals in silages of sorghum cv. IPA 2502 irrigated with different leaching fractions of brackish water. Sorghum cultivation was carried out in the field in a randomised block design, with four replications and four irrigation leaching fractions (0%, 5%, 10%, and 15%). From the harvested plant material, five silos per treatment, with five repetitions, were arranged in a completely randomised design for ensiling. Leaching fractions did not alter the levels of nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur in sorghum. The sodium content showed a quadratic response to the leaching fractions, which was also observed for iron, manganese, and chloride. In silage, an increasing linear effect was found for nitrogen, whereas for phosphorus, potassium, and sulfur, the contents were reduced with the addition of the leaching fraction. The contents of copper, iron, zinc, and chloride in silages responded in a quadratic way. The use of brackish water, especially the 15% leaching fraction, in the cultivation of sorghum enhances the mineral contents and the recovery of some macro- and micro-nutrients after the ensiling process. Full article

In large hayfields belonging to intensive dairy systems, satellite remote-sensing data can be useful to determine the hayfield yield and quality efficiently. In this study, we compared the land survey data of hayfield yield, and its quality parameters such as crude protein and neutral detergent fiber digestibility (NDF), with the Sentinel-2 satellite image data for thirteen hayfield paddocks in Kamishihoro region, Hokkaido, Japan. Commonly used indices derived from the satellite image data, including the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), were used to assess the hayfield yield and quality. In this region, hayfields are usually harvested twice yearly, in early summer (first harvest) and late summer (second harvest). As result, the Sentinel-2 data could predict the pasture growth and quality for the first harvest better than those for the second harvest. The EVI and the index based on the bands B8a and B7 were the best predictors for the biomass and NDF for the first harvest, respectively. However, the satellite-image-based predictors were not found for the second harvest. Towards the second harvest season, the color of the hayfield surface became more heterogeneous because of the flowering of weeds and uneven pasture growth, which made it challenging to predict pasture growth based on the remote-sensing data. Our land survey approach (quadrat-based sampling from a small area) should also be improved to compare the remote-sensing data and the pasture with uneven growth. Full article

Nitrogen (N) is a nutrient used worldwide in pasture fertilization. However, it is a very volatile element. Furthermore, inappropriate use promotes environmental pollution and economic losses. The present study was carried out to evaluate the effects of the N source on the productivity and N utilization efficiency in Xaraés grass (Brachiaria brizantha cv. Xaraés) under tropical conditions. The randomized complete block design was used in a 3 × 2 × 4 factorial scheme: three seasons (rainy, dry, and transition), two N sources (fast-release = conventional urea, and slow-release = treated urea), and four N doses (0, 80, 160, and 240 kg N/ha/year). Forage accumulation per day differed (p < 0.0001) with the season and N dose. The interaction between those showed a positive linear effect (p < 0.0001) during the rainy season and transition. With increasing N doses, there was a linear increase in annual dry matter production and N accumulation. However, the N utilization efficiency (p < 0.0001) was reduced. Nitrogen sources did not affect forage accumulation and N utilization efficiency. Therefore, it is not recommended to replace fast-release nitrogen fertilization (conventional urea source) with a urease inhibitor (slow-release N source), promoting benefits with lower production costs. Full article

The alpine grasslands of the Qinghai–Tibet Plateau are one of the most famous grazing ecosystems in the world, providing a variety of ecosystem functions and services. The rate of grassland degradation has been slowed by the implementation of national grassland restoration projects, but the degradation of grasslands on the Qinghai–Tibet Plateau has not yet been fundamentally reversed, and some grasslands are still degraded to varying degrees. The main causes of grassland degradation on the Qinghai–Tibet Plateau are both human and natural factors. Human factors include overgrazing, over-cultivation, indiscriminate digging and mining, mineral resource development, infrastructure construction and use, and tourism development. Natural factors include climate change, wildlife destruction, pests, etc. Based on the principles of restoration ecology, a number of effective practices and integrated management responses for restoring degraded grasslands have been developed on the Qinghai–Tibet Plateau. The degraded grassland restoration practices include fencing, fertilization, sown grassland establishment, rodent control, and grazing management. Based on these practices, the comprehensive restoration of degraded grasslands and the establishment and sustainable management of sown grasslands in the alpine grasslands of the Qinghai–Tibet Plateau should be further strengthened, and research on the mechanisms of grassland degradation and restoration should be further developed. Full article

Distinguishing the contributions of different vegetation cover such as shrubs and grasses components into the primary production in arid and semi-arid rangelands is a key step to understanding changes at a landscape scale. The aim was to assess the contribution of shrubs, grasses and bare soil components into a total biophysical variable at a patch level, and the relationship between that biophysical variable and remote sensing vegetation index, in a grass–shrub steppe from North-West Patagonia, Argentina. We conducted a field survey in the period 2015–2017 to analyzing the relationship between monthly values of Normalized Difference Vegetation Index (NDVI) of two grasses, two shrub species and bare soil, weighted by their cover area at a patch level, and the concomitant patch NDVI records, respectively. The contribution of the patch components to the total NDVI value at a patch level was additive. The relationship between the weighted NDVI of patch components and the concomitant NDVI value at a patch level along time was linear for perennial grasses and deciduous shrub–grass patches, but linearity was not significant for most perennial shrub–grass patches. Differences among patch compositions and their surface reflectance suggest the need to move forward in a more precise distinction of the floristic composition of patches, to better understanding their contribution to NDVI temporal dynamics at a landscape scale. Full article

Large crabgrass (Digitaria sanguinalis) is one of the most problematic weeds in summer crops in Argentina. Emergence throughout the season of several cohorts allows the weed to escape postemergence control. Demographic models are useful tools to understand and compare the effect of different agronomic management decisions on weed population growth, as well as to identify critical functional stages that affect population growth rates. The objectives of this work were (i) to study population dynamics of D. sanguinalis in soybean, (ii) to determine the effect of glyphosate application timing on weed demographic parameters and soybean yield losses, and (iii) to evaluate the effect of weed density on soybean yield loss. A field experiment was conducted in two locations, in a completely randomized design with three replicates. Treatments included a control without glyphosate and glyphosate applied at soybean stages V4 or R1. The demographic stages (initial seedbank, seedlings, and adult plants) and parameters (establishment, survival, and fecundity) were estimated. Reproductive organs were evaluated in each cohort, including raceme per plant, spikelets per raceme, and seeds per spikelet. Weed and crop biomass and yield crop were assessed at harvest. Three cohorts were identified, the first of which emerged in November and contributed 93% of the total seedlings and 71% of the total adults. Glyphosate applied at V4 reduced the survival rate of the first cohort, as well as the total shoot biomass and the fecundity rate, increasing the biomass and crop grain yield. Both application timings affected tillers per plant, racemes per tiller, and fertile spikelets per raceme. Glyphosate at R1 did not effectively reduce weed competition, but reduced seed production as application at V4. Yield losses estimated with the model of the rectangular hyperbola according to weed density showed a yield loss at low densities (I) of 18%, and a maximum yield loss (A) of 82%. To avoid yield losses, herbicide applications targeting the first cohort are more effective than later applications targeting subsequent cohorts. However, at both times glyphosate applications reduced the number of seeds entering the seedbank, and therefore the population growth rate. Full article

The objective of this study was to evaluate the morphological characteristics, yield and chemical composition of grasses in degraded areas subjected to pasture recovery methods. The randomized block design in a factorial scheme (4 × 5) with four replications (blocks) was used. The first factor was composed of four methods of pasture recovery: Closed pasture (CLP); Weed control (WC); Soil fertilization (SF); and Weed control + Soil fertilization (WC + SF). The second factor was composed of five species used for pasture recovery: Brachiaria brizantha cv. Marandu, Brachiaria brizantha cv. MG5, Brachiaria brizantha cv. MG4, Andropogon gayanus cv. Planaltina and Panicum maximum cv. Mombaça. The structural characteristics of green biomass yield, dry biomass yield and chemical composition were assessed in those grasses. An effect of the interaction (p < 0.05) between forage species and recovery methods on number of clumps, plant height and clump diameter, with superiority for cultivar MG4 in the WC + SF method. The green biomass yield was low in the evaluated grasses because of the advanced stage of the degradation of the pastures. Dry biomass yields increased (p < 0.05) when the WC + SF method was adopted, with a good response of grass MG4. There was an interaction (p < 0.05) between species and recovery methods on dry matter, mineral matter and neutral detergent fiber contents of the grasses, especially Marandu grass. The different types of grasses responded positively to the methods of pasture recovery with increased biomass and nutritional quality. Full article

For aesthetic considerations, grass clippings are removed from lawns during mowing. When turfgrass clippings are returned, this practice is called “mulching” or grasscycling. Thus, grasscycling has increasingly become a standard practice for low-input lawns managed under a simpler maintenance system, and grasscycling has many environmental benefits. Primarily, grasscycling facilitates an increase in soil nitrogen content and soil carbon sequestered by the turfgrass ecosystem. Several studies reported that grasscycling positively influences turfgrass colour and quality. When clippings are returned, turfgrass colour and quality can be maintained with a lower amount of fertilisation than turfgrass with clipping removal. Together with these positive effects, grasscycling practices can contribute to an increase of thatch in the turfgrass sward, while its influence on weed invasion is still questionable. This grasscycling practice can result in a maintenance cost-savings and represent a low-input approach to turfgrass management in terms of nutrients returned and utilised by the turfgrass, and with carbon (C) emissions mitigated and C sequestered. The unwelcome appearance linked to grass clipping residues and vegetation on the turfgrass canopy can be easily obviated by the use of machinery that delivers clippings forcefully toward the ground to incorporate them into the verdure or by using mowers that produce clippings small enough to be returned and quickly decomposed. Full article

Most Brazilian pastures are in some stage of degradation, either by the reduction of soil fertility or inadequate management. The objective of this study was to diagnose the stage of pasture degradation and the diagnosis and management of the spatial variability of available phosphorus (P) and potassium (K⁺). A total of 100 soil samples were collected at a depth of 0–20 cm for available P and K⁺ contents determination. Geostatistical analyses of the obtained data were carried out to produce maps of the spatial distribution of available P and K⁺, using kriging, and allow the recommendation of fertilizers doses. The cost/benefit ratio of fertilizer recommendation and application was evaluated at fixed and variable rates. The different stages of pasture degradation were directly related to the reduction of soil fertility, as well as to the adopted management. The variability of soil available P and K⁺ presented spatial dependence, and the pattern of distribution resulted in the stage of the pasture degradation. The diagnosis of the level of pasture degradation associated with the use of geostatistical techniques under a precision agriculture perspective favors the efficient use of fertilizers, as well as correct decision-making and cost reduction regarding soil management. Full article

The Sanjiang Plain is famous for its concentrated distribution of natural wet grasslands. These wet grasslands are an important source of seasonal pasture or hay in the area. However, changes in community structure and ecosystem function have already occurred in wet grasslands because of overgrazing and climate change, resulting in severe grassland degradation. Exploring a reasonable grazing management strategy is crucial for improving grassland species diversity, increasing grassland productivity, and maintaining sustainable grassland utilization. We investigated the effects of five grazing management (GM) strategies (no grazing through the growing season (CK), spring grazing exclusion (Spr-GE), summer grazing exclusion (Sum-GE)), autumn grazing exclusion (Aut-GE), and grazing through the growing season (G)) on the productivity, community composition and structure of wet grasslands in the Sanjiang Plain under three grazing intensities (GI) (light (L), moderate (M), and heavy (H)). Results showed that Spr-GE and Sum-GE were beneficial in increasing total aboveground biomass (AGB), but decreased plant community diversity in Spr-GE due to increased intraspecies and interspecies competition. The exclusion of different seasonal grazings changed the composition of plant communities. At the level of functional groups and dominant species, Spr-GE had a significant effect on most functional groups and dominant species’ characteristics, while Aut-GE had little effect on most functional groups and dominant species’ characteristics. However, different functional groups and dominant species had different responses to seasonal grazing exclusion. In addition, under M, there were significantly improved grassland total AGB and PF AGB. The results indicated that Spr-GE with M may be an effective livestock-management strategy to protect grassland vegetation and community diversity, as well as to restore degraded grassland. Full article

Winter annual cereal forages perform well in semiarid, subtropical regions forming, a significant component of livestock operations for autumn through spring stocker cattle (Bos taurus) backgrounding in either grazeout or graze-grain systems; however, little information is available about their relative seasonal productivity and animal preference. Seasonal growth and regrowth under grazing and grazing preference of oat (Avena sativa), rye (Secale cereale), triticale (×Triticosecale rimpaui Wittm.), and wheat (Triticum aestivum) were compared over two years at New Mexico State University’s Rex E. Kirksey Agricultural Science Center at Tucumcari. Seasonlong (Nov–Apr) average forage dry matter yield was rye > oat > wheat > triticale (5.03, 4.44, 3.58, and 2.79 Mg ha⁻¹, respectively; p < 0.0001). Rye also had greater average monthly growth than the other cereals, among which there was no difference (1.58, 1.05, 0.96, and 0.85 Mg ha⁻¹ mo⁻¹ for rye, oat, wheat, and triticale, respectively; p < 0.0331). Growth of ungrazed cereals was reduced in mid-winter and regrowth of grazed forage did not equal removal by growing cattle. When given a preference and allowed to deplete available forage, growing cattle preferred oat followed by rye, then wheat and triticale. Regrowth of grazed forage did not differ among cereals. Full article