Despite high nutritional and economic value, alfalfa yield has not been improved in the United States. Soil moisture critically influences alfalfa's yield and quality, affecting its physiological processes, nutrient uptake, and stand growth. Additionally, the maturity stage at harvest can significantly impact both hay yield and quality. Thus, this study aimed to assess the effect of different soil moisture levels and harvesting times on forage yield, nutritive value, and the overall profitability of commercially cultivated alfalfa.
Two conventional and three lower-lignin alfalfa varieties were planted in a randomized complete block with split plot design under drought, rainfed, and irrigation conditions in 2020 in Manhattan, Kansas, USA. The dry matter yield (DMY) and forage nutritive value were evaluated at late bud, early flowering, and 7 days after early flowering stages, respectively.
DMY varied with production year, soil water availability, and growth stages, with drought conditions causing a decline in DMY of 5% to 38% in the second production year. Water conditions and maturity stages influenced crude protein (CP) and in vitro dry matter digestibility (IVDMD). Higher soil moisture and advancing maturity stages negatively impacted CP, IVDMD, and relative forage quality. The study revealed net profit margins of 62%, 64%, and 52% for drought-prone, rainfed, and irrigated production, respectively.
Harvest timing and irrigation practices were found to have substantial implications for forage yield and nutritive value of alfalfa. The yield-quality trade-off differed under drought and irrigation, with early harvesting leading to lower yields but higher protein content and digestibility. The study findings provide potential guidance for improving alfalfa hay yield, quality, and profitability.
Soil organic C and N data from privately managed pastures in the southeastern United States are relatively scant.
A 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.
Soil 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).
This 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.
The pioneer Amaranthaceae species sand rice (Agriophyllum squarrosum) is an annual psammophyte that is widely distributed in the deserts and sand fields of northern China. The well-balanced nutritional values, long consumption history, and extreme stress tolerance of sand rice have fascinated scientists, prompting its development as a climate-resilient crop. Sand rice has been successfully introduced and cultivated on sandy and loess lands over the past decade, while large-scale artificial planting has been carried out in the Ulan Buh and Tengger deserts. However, the yield is far below the maximum potential, as estimated by the highest yield per plant ever found in the Tengger desert during our survey of wild populations. The current domestication of sand rice relies mainly on natural selection and mutagenesis breeding. A few elite lines with modified agronomic traits, such as compact architecture, high productivity, reduced trichomes, and short plant stature, have been developed from natural populations and a chemical mutagenesis library. Breeding new cultivars and broader cultivation of sand rice in deserts and marginal lands will stimulate economic growth and diversify the food supply, especially for the area west of the Hu Huanyong Line, thus contributing to environmental sustainability in northern China.
More frequent and severe drought events due to climate change pose a major challenge for sustainable forage production in managed grasslands. This study investigated whether multispecies grassland communities can provide greater resistance to and/or recovery from drought compared to monoculture communities.
Mesocosms of Lolium perenne L., Cichorium intybus L., Trifolium repens L. and Trifolium pratense L. were established as monocultures, and a four-species mixture. A drought gradient with five levels of water supply ranging from a mild to a severe treatment was applied for 10 weeks, in each of 2 years. Shoot biomass was harvested to assess drought resistance, drought recovery and annual yields. Root mass density and specific root length were measured in Year 2.
Across the drought gradient, four-species communities had significantly larger annual yields than each of the four monocultures, indicating transgressive overyielding. This was despite relatively low drought resistance for four-species communities compared with L. perenne and C. intybus monocultures. Recovery of yields following drought was high for all communities.
Multispecies swards with complementary traits can provide a viable adaptation option across a wide range of drought severities. Application of a stress gradient methodology allowed a more detailed understanding of stress responses.
Selective grazing creates stable patches of contrasting sward height, thereby providing different growth conditions for the grass sward above and below ground and potentially affecting soil organic carbon (SOC) stocks. We hypothesized that the presence of patches leads to greater spatial variability in belowground biomass (BGB) and SOC stocks than occurs between pastures managed under different stocking intensities.
A long-term grazing experiment consisting of three stocking intensities was used for this study. We studied BGB, SOC, and soil total nitrogen (Ntot) stocks in the 0–15 cm soil depth. Shannon diversity of plant species, soil bulk density, soil phosphorus, potassium, and magnesium contents were considered.
There were no significant effects of patch or stocking intensity on BGB, SOC, and Ntot stocks. Short patches had a greater Shannon diversity than tall patches (p < 0.05) and plant-available nutrients in soil correlated positively with sward height (p < 0.05).
We conclude from the current results and previous studies that higher plant species diversity with lower soil nutrient contents in short-patch areas and higher nutrient contents together with light competition in tall-patch areas might balance each other out with respect to BGB and SOC stocks.
The incorporation of legumes, specifically alfalfa (Medicago sativa L.), into bermudagrass (Cynodon spp.)-based pasture systems in the southeastern United States has increased in recent years as an alternative to synthetic nitrogen (N) fertilization.
A small plot evaluation was conducted in Shorter, Alabama, and Tifton, Georgia, USA, to evaluate the impact of harvest height (HH) and harvest frequency (HF) on agronomic characteristics of alfalfa+bermudagrass mixtures in southeastern United States.
Results from both locations revealed that the longer the HF and the shorter the HH, the greater the alfalfa retention was in the stand (p < 0.01). HH did not impact any of the reported nutritive value parameters, while longer HF resulted in lower total digestible nutrients, lower crude protein, higher acid detergent fiber, and lower 48 h in vitro dry matter digestibility (p < 0.01). Both HH and HF impacted forage accumulation at both locations (p < 0.01). HH resulted in different trends at each location, while longer frequencies generally increased forage accumulation.
This research confirmed recent findings from comparable evaluations in the southeastern United States, in that increasing HH and decreasing HF improved alfalfa retention while having a negligible effect on nutritive value or forage accumulation.
Agricultural yields have increased continuously over the last few decades. However, a focus solely on production can harm the environment. Diversification of agriculture has been suggested to increase production and sustainability. Biodiversity experiments showed positive effects on ecosystems and productivity. However, application of these results to intensively managed grasslands has been questioned due to differences in plant species and management regimes. Research on whether diversity can benefit multifunctionality, that is, an integrated index of multiple ecosystem functions, under intensive management, is still scarce.
To address this, we manipulated plant species richness from one to six species spanning three functional groups (legumes, herbs, and grasses) in intensively managed multispecies grassland leys and examined seven ecosystem functions.
We found that multifunctionality increased with functional group and species richness. Legume+herb mixtures showed high multifunctionality, while grass monocultures and mixtures with high proportions of grasses had low multifunctionality. Different plant species and plant communities drove different ecosystem functions. Legumes and herbs improved productivity and water availability, while grasses enhanced invasion resistance. These results indicate that multifunctionality and individual ecosystem functions can be promoted through targeted combinations of plants with complementary ecological traits.
Plant diversity can improve multifunctionality also under intensive management, potentially benefitting agroeconomics and sustainability.
Soil and water salinity are increasing problems worldwide, causing significantly reduced crop yields. Alfalfa (Medicago sativa L.) is often listed as salt-sensitive, but field testing of improved cultivars is limited. Forage systems and improved high-quality alfalfa varieties are needed to enable crop production under high salinity (HS) conditions.
The objective of this study was to measure the yield and quality response of alfalfa to high saline conditions in the field and to document the relative saline tolerance of its varieties. HS irrigation water (electrical conductivity of water, or ECw 8.0–11.0 dS m−1) was applied to 33 nondormant alfalfa cultivars and were compared with low salinity (LS) treatments (ECw 0.5–1.2 dS m−1) over 4 years in a Mediterranean environment on a clay loam soil utilizing a split-plot design. Crops were harvested seven to eight times per year, and the forage quality was measured on selected harvests utilizing near-infrared spectroscopy.
The average yield loss due to HS treatment was 23.9% compared with LS treatment, but yields averaged 23.4 Mg ha−1 under HS over the 3 full years of production. This level of production is considered to be economically viable in this region. Differences in salinity tolerance between lines were identified in the field; individual cultivars lost 5%–35% of their LS yield when grown under HS conditions. Forage quality was significantly improved under HS versus LS conditions, but improvements were negatively correlated with biomass yield (R2 > 0.81), similar to responses observed in drought-stressed alfalfa.
These yield results confirm greenhouse studies, indicating that alfalfa is highly salt tolerant once established in the field, with potential for further improvement with tolerant cultivars. Salinity tolerance should be chosen based on total biomass yield as well as on the salinity tolerance index (HS yield relative to LS yield). Agronomic practices to mitigate salinity and sodicity are critical, along with improved cultivars.
Due to the effects of climate change and overgrazing in recent decades, alternative stable states in the alpine Kobresia meadow degradation process have coexisted in the same geographical and climatic environment, with variations occurring among microsites.
We used a space-for-time substitution approach to explore the synergies of microsite variation according to its numerical characteristics and the proportion of each stable state at various stages of succession in alpine Kobresia meadows on the Qinghai–Tibetan Plateau.
(1) The highest average aboveground biomass in summer was 196.2 ± 20.3 g m−2, with significantly higher levels of biomass in ≤3.65 sheep unit ha−1 than in other levels of grazing intensity, while the parameters showed no significant differences among grazing intensity levels in >3.65 sheep unit ha−1. (2) The importance of plant functional groups, aboveground biomass, and niche breadth of Poaceae and Cyperaceae significantly decreased as the grazing intensity increased. (3) The effects of ≥0°C accumulated temperature, total precipitation, altitude, longitude, and latitude cumulatively contributed less than 20% of the variation in the distribution of functional group characteristics across microsites.
(1) Overgrazing decreases primary production in alpine Kobresia meadows, but ecosystem responses regulate plant community structure and botanical components so as to partially counteract grazing disturbance. (2) Overgrazing changed the proportion of microsites, which in turn led to regime shift in the plant community and subsequent synergies between the microsites of plant communities and their stable states.
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