Alfalfa Stands Research Articles

Optimizing potassium applications and harvest strategies to boost productivity of depleting alfalfa stands

Optimizing potassium applications and harvest strategies to boost productivity of depleting alfalfa stands

Biological Decline of Alfalfa Is Accompanied by Negative Succession of Rhizosphere Soil Microbial Communities.

The growth and biological decline of alfalfa may be linked to the rhizosphere microbiome. However, plant-microbe interactions in the rhizosphere of alfalfa and associated microbial community variations with stand age remain elusive. This study explored the successional pattern of rhizosphere microbial communities across different aged alfalfa stands and its relationship with alfalfa decline. Rhizosphere soils were collected from 2- and 6-year-old alfalfa stands. Control soils were collected from interspaces between alfalfa plants in the same stands. Soil bacterial and fungal communities were characterized by 16S and ITS rRNA gene sequencing, respectively. Specific microbial taxa colonized the rhizosphere soils, but not the control soils. The rhizosphere-specific taxa mainly included potentially beneficial genera (e.g., Dechloromonas, Verrucomicrobium) in the young stand and harmful genera (e.g., Peziza, Campylocarpon) in the old stand. Alfalfa roots regulated soil microbial communities by selective promotion or inhibition of distinct taxa. The majority of time-enriched taxa were reported as harmful fungi, whose relative abundances were negatively correlated with plant traits. Time-depleted taxa were mostly known as beneficial bacteria, which had relative abundances positively correlated with plant traits. The relative abundances of functional bacterial genes associated with vancomycin biosynthesis, zeatin biosynthesis, and amino acid metabolism trended lower in rhizosphere soils from the old stand. An upward trend was observed for fungal pathogens and wood saprotrophs with increasing stand age. The results suggest that root activity drives the negative succession of rhizosphere microbial communities during alfalfa decline in old stands.

Efikasnost herbicida u suzbijanju korova u lucerki

Alfalfa is one of the most important perennial fodder crops, and it is also the most economical. Alfalfa provides first class fodder that is suitable for feeding all livestock, especially ruminants. Grass and broadleaf weeds are a serious threat to the quality and viability of alfalfa stands. Weeds can reduce the nutritional value of the crop and cause significant reductions in yield, as they compete aggressively for water, nutrients, sunlight, and space. In this study, herbicides (Butoxone DB, Agil, Basagran, Corum, Fusilade forte, Pulsar and Focus ultra) were used for controlling weeds in alfalfa. The presence of annual and perennial weeds, typical of alfalfa plantations: Capsella bursa-pastoris, Stellaria media, Lamium amplexicaule, Viola arvensis, Amaranthus retroflexus, Setaria spp., Sorghum halepense, Cirsium arvense, Plantago lanceolate, Rumex crispus and others, was observed on the tested surfaces. Our research has shown that the most effective herbicides are Basagran, Butoxone DB and Corum, which are intended to suppress broadleaf weeds. Meanwhile, herbicides Fusilade forte and Pulsar proved to be very effective in controlling grass weeds. A very good reaction was also observed with the combinations of herbicides Pulsar + Fusilade forte and Pulsar + Basagran, as these combinations expand the spectrum of activity to the grass and broadleaf weeds. The aim of this paper was to determine which herbicide is most effective in controlling weeds in alfalfa.

Effects of Intercropping, Nitrogen Fertilization and Corn Plant Density on Yield, Crude Protein Accumulation and Ensiling Characteristics of Silage Corn Interseeded into Alfalfa Stand

Interseeding silage corn into an alfalfa stand following its spring harvests to produce mixed silage would feasibly break the restriction of alfalfa production during a hot-rainy summer. In this 2-yr experiment, the alfalfa–silage corn intercropping system (AC) with nitrogen (N) fertilization rates of 0, 60, 120, and 180 kg N ha−1 and corn plant densities of 30,000, 45,000, and 60,000 plants ha−1 was compared with the monocultured corn (CK) managed using the local farmers’ practice. Intercropping with alfalfa significantly decreased the dry matter (DM) yield of the corn by 31.5% on average, while increasing the N application rate and corn plant density promoted DM yield and crude protein (CP) accumulation of the intercropped corn, and the intercropping system could achieve the same CP yield as CK—it did in most cases. Although the DM contents, pH values, and NH3-N concentrations were decreased in the mixed silage, its fermentation quality was not reduced and the CP, water soluble carbohydrates, and lactic acid contents were dramatically increased by 16.3%, 17.8%, and 72.9% compared with those of CK, respectively. For the opposite effects of N fertilization and corn density on silage quality, the treatment combination with a medium corn density (45,000 plants ha−1) fertilized at a medium N rate (120 kg N ha−1) was evaluated as the optimum for more balanced system productivity, silage nutritive values and fermentative characteristics during the coexisting period.

Productivity of indigenous alfalfa (Medicago sativa) cultivar depending on agricultural practices on sierozem soils in South Kazakhstan

In Turkestan region of South Kazakhstan has large areas of fertile sierozem soils that are important for crop production and its accompanying economic development. And also, alfalfa (Medicago sativa) is an important forage crop grown for seed production. The soils are fertile loams, but because of the regions dry environment, they need to be irrigated. Field experiments were conducted from 2017 to 2020 on one-year or older alfalfa stands grown for seed production at various plots on sierozem soils in rainfed areas of Turkestan region to determine the influence of agricultural practices such as fertilizer use, pesticide use and conventional tillage on seed yield and dry hay of alfalfa stands. The findings of field research experiments indicated that agricultural practices of fertilizer use, pesticide use and conventional tillage was essential to obtain maximum seed yield and dry hay of alfalfa. But, it was determined that the best outputs tended to be obtained with Fertilizer use + Pesticide use + Conventional tillage.

Performance, carcass and meat traits of beef steers finished on small-grain winter annuals in winter or on alfalfa pasture in summer

Performance and carcass traits of beef steers finished on small-grain winter annual pastures (SGWA) or alfalfa were compared. Treatments consisted of pure stands of cereal rye, triticale, wheat or alfalfa (Rye, Trit, Wht, and Alf, respectively). The 3 SGWA species were grazed during winter and early spring. Alfalfa was grazed during spring and summer. Three pasture replicates were assigned to each treatment with 10 animals each. A minimum of 7-mm subcutaneous rib fat thickness (determined by ultrasound) was defined as slaughter endpoint. After a 98-d finishing period all animals from Rye, Trit and Wht reached the target, and were ready for harvest. Alfalfa animals were slaughtered after 120 days. After slaughter, carcasses were individually graded and weighed to determine hot carcass weight (HCW) and hot carcass yield (HCY) was calculated. Seventy-two h post-slaughter, a section of steaks including the longissimus thoracis muscle (LT) was removed from the left side of each carcass for analysis including rib fat thickness (RFT), LT area (LTA), Warner-Bratzler-shear force (WBsf), drip-loss, cooking loss, instrumental color, muscle pH, sensory analysis, intramuscular fat content and lipid profile. Proximate composition, and lipid profiles of pastures offered were also determined. Alf animals had lower (P < 0.01) ADG than SGWA animals. Alfalfa animals took 22 days longer to reach the slaughter point. However, no pasture effects were detected (P ≥ 0.14) for HCY, LTA, RFT, WBsf, pH, muscle a* and b*, and subcutaneous fat L*, a* and b* color parameters. Muscle L* was greater (P < 0.05) and drip and cooking loss were lower (P ≤ 0.05) for Alf. Sensory panel scored Alf beef of greater (P < 0.01) juiciness, tenderness and beef-flavor. Rye beef was attributed highest off-flavor score. Alfalfa and Wht beef showed similar (P = 0.40) FA content, higher (P ≤ 0.02) than Rye and Trit beef. Rye beef had the lowest (P ≤ 0.02) FA content. Within the FA fraction, Alf had lower (P ≤ 0.02) proportion of SFA, greater t-MUFA content, greater (P ≤ 0.01) total n-3 concentration and the lowest n-6/n-3 ratio (P ≤ 0.01). Alfalfa beef resulted in greater (P ≤ 0.01) total CLA concentration. Although lipid profiles of forages related to observations in lipid profiles of beef, differences in drip and cooking loss and sensory attributes of beef that favored of alfalfa finishing were not explained in animal performance and fatness.

Species Complex and Temporal Associations between Coccinellids and Aphids in Alfalfa Stands in Spain.

Simple SummaryAlfalfa is the main fodder crop of the irrigated crop systems of northern Spain, as well as many Mediterranean countries. Alfalfa crops are damaged by some pest species but are also considered to be vast reservoirs of natural enemies of these pests. However, in Europe, the relationships between these pests and their natural enemies have been poorly studied. The aim of this study was to fill this gap in the knowledge. Therefore, we characterized the coccinellid species complex, identifying sixteen species, and the numerical relationships of the two that were most prevalent—Coccinella septempunctata and Hippodamia variegata—with the different aphid species, which are considered one of the alfalfa pests. The numerical relationships were separately studied in each of the alfalfa growing periods between cuttings (intercuts). Whereas the abundance of C. septempunctata was correlated with that of A. pisum in the second alfalfa intercut, H. variegata was mainly correlated with the abundance of T. trifolii in the fourth intercut as well as with the overall aphid abundance in the fifth intercut. This study helps to increase the knowledge on the predator–prey relationships, which is crucial for the proper pest management of alfalfa and the agricultural ecosystems in which it is included.Alfalfa is known to be an important reservoir harboring natural enemies. The reduction in insecticide sprayings in recent years has allowed us to study the coccinellid species complex in this crop and the relationship between these predators and aphids. Alfalfa was sampled by sweep-netting throughout its productive period in several commercial stands each year between 2010 and 2021. The numbers and species of aphids and coccinellids were recorded. Sixteen coccinellid species were found. Coccinella septempunctata and Hippodamia variegata were, by far, the most prevalent species, with the former dominating during the first and second intercuts, whereas the latter dominated from the third to the fifth intercut. Acyrthosiphon pisum and Therioaphis trifolii were the most abundant aphid species, peaking in the second and fourth intercuts, respectively. Positive correlations were found between the abundance of C. septempunctata and A. pisum at the second intercut, between H. variegata and T. trifolii at the fourth intercut, and between H. variegata and the total number of aphids in the fifth intercut. This study helps to increase the knowledge on the predator–prey relationships of this crop and allows for designing strategies of conservation biological control against aphids.

Tillage method and glyphosate‐resistant alfalfa termination timing affect soil properties and subsequent corn yield

AbstractApplication of glyphosate [N‐(phosphonomethyl) glycine]‐containing herbicides and tillage, alone or in combination, has been the standard for removing declining alfalfa (Medicago sativa L.) stands. With glyphosate no longer an option to control glyphosate‐resistant alfalfa, different termination strategies are needed. Field studies across four site‐years in Utah evaluated the effect of tillage type and timing (fall conventional till, spring conventional till, fall strip‐till, spring strip‐till, and no‐till) and herbicide timing (fall, spring, in‐crop, and no herbicide) of 2,4‐D (2,4‐dichlorophenoxyacetic acid) and dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) on penetration resistance, alfalfa regrowth, corn (Zea mays L.) emergence rate, and silage corn yield. Across tillage treatments, fall, spring, and in‐crop herbicide timings compared with no herbicide reduced alfalfa stem count and biomass by at least 74 and 92%, respectively. Emergence rate was greatest under fall and spring conventional till or spring strip‐till compared with fall strip‐till or no‐till. Silage corn yield was greatest and similar with fall or spring herbicide applications for all tillage systems and conventional tillage with an in‐crop herbicide application (19–27 Mg ha−1), followed by in‐crop herbicide application for conservation tillage systems and fall and spring conventional till without herbicide application (14–20 Mg ha−1), and lastly when only conservation tillage was used to terminate alfalfa (5–15 Mg ha−1). Silage corn yield can be optimized when glyphosate‐resistant alfalfa is terminated with herbicides prior to planting, regardless of tillage type or timing. Termination of glyphosate‐resistant alfalfa by herbicides after corn emergence, depending on tillage, reduces silage corn yield 9–19%.

Forage yield, water use efficiency, and soil fertility response to alfalfa growing age in the semiarid Loess Plateau of China

Water availability is a major constraint for crop production in the Loess Plateau of China; thus, improving water use efficiency (WUE) is a main research target. The impact of alfalfa (Medicago sativa L.) growing age on forage yield, WUE, soil water storage, and soil fertility were examined in a 15-yr study in the western Loess Plateau of China. The results of this study indicate that long-term continuous production of alfalfa aggravated the soil water deficit and reduced soil available phosphorus (AP) and the ratio of soil organic carbon to soil total nitrogen, but increased soil organic carbon, soil total nitrogen, and the ratios of soil organic carbon to soil available phosphorus and soil total nitrogen to soil total phosphorus. After the ninth year of alfalfa production, the greatest soil water storage deficit degree was found in the 0–80 cm soil layer (63 %), followed by the 200–300 (57 %) and 80–200 cm (55 %) soil layers. Forage yield and WUE of alfalfa reached their greatest values following six- to nine-yr-old stands, and then decreased gradually. These results suggest that the yield decline with long-term stands of alfalfa may be related to reductions in soil water storage and AP, and their interaction, and the optimal alfalfa growing age should not extend beyond nine years in semiarid conditions.

Does Alfalfa Stand Up for the Claim "The Father of All Foods"?

Does Alfalfa Stand Up for the Claim "The Father of All Foods"?

AAC Glenview sainfoin (Onobrychis viciifoila subsp. viciifolia)

AAC Glenview sainfoin, tested as LRC 4342, was developed by the Agriculture and Agri-Food Canada (AAFC) Lethbridge Research and Development Centre, Lethbridge, Alberta. This cultivar was derived from parental clones selected for improved forage yield in mixed stands with alfalfa under grazing and regrowth after grazing. When grown under irrigated and rainfed conditions in western Canada, Glenview out yielded Nova (check) by 21% in pure stands over 37 location–years and 19% in mixed stands with alfalfa over 17 location–years. This cultivar flowers and matures about 8 d earlier than Nova and has slightly larger seed than Nova (24.7 g 1000 seeds−1 vs 20 g 1000 seeds−1). It can be grown for hay and pasture in pure stands but Glenview is well suited for mixed sainfoin–alfalfa stands. Breeder seed for the cultivar will be produced by AAFC and the multiplication and distribution rights were awarded to Monarch Feeders Ltd., Monarch, AB, Canada.

Forage yield, water- and solar radiation-productivities of perennial pastures and annual crops sequences in the south-eastern Pampas of Argentina

Livestock production systems of Argentina show an ongoing process of change in the composition of their forage base, with a gradual increase in the proportion of their area assigned to forage crop sequences (FCS) −in particular that involving successive winter and summer annual forage crops–, at the expense of the area assigned to perennial pastures (PP). However, there are several concerns regarding the efficient use of available environmental resources due to differences in the extent of the establishment periods and due to the occurrence of fallow periods in FCS, as well as regarding the species involved in these systems. Therefore, the main objective of this study was to evaluate the water (WP) and solar radiation productivity (RP) of PP [pure stands of alfalfa (Medicago sativa L.), fertilized and unfertilized stands of tall fescue (Festuca arundinacea Schreb.), and fertilized and unfertilized mixed stands of alfalfa/tall fescue] and FCS [including a summer alternative and oats (Avena sativa L.); the summer alternative was either maize (Zea mays L.) or intercropped maize/soybean (Glycine max L.)] through the analysis of their components, i.e. water (WC) and radiation capture (RC), and their water (WUE) and radiation use efficiency (RUE). Resource capture (WC and RC) was defined as the ratio between captured (evapotranspiration and intercepted solar radiation) and annual available resource (rainfall and incident solar radiation). Resource use efficiency (WUE and RUE) was computed as the dry matter (DM) yield per unit of captured resource. A field experiment was conducted during two consecutive years under rainfed conditions and under non-limiting nitrogen availability in the south-eastern Pampas of Argentina. Perennial pastures were evaluated during both their initial establishment year (Y1) and when already fully established (Y2). Annual-based forage DM yield ranged between 13.0 and 32.4 Mg ha−1 in Y1 and between 5.1 and 23.5 Mg ha−1 in Y2. Differences in resource capture between PP and FCS were directly associated with the crop establishment and fallow periods depending on the nature of the considered resource. The highest WP (2.75–3.64 g DM m−2 mm−1) and RP (0.93–1.42 g DM MJ−1) were reached by FCS, which did not differ (P > 0.05) from that of fully established fertilized PP. Our results demonstrate that resource productivity in FCS is not necessarily higher than for PP, once PP are fully established.

Soil water storage deficit of alfalfa (Medicago sativa) grasslands along ages in arid area (China)

Alfalfa (Medicago sativa) is a high-yield and high drought-tolerant perennial forage crop, which take up water from deep soil layers by its deep root system. Long-term cultivation of alfalfa without a sufficient water supply aggravates soil water storage deficits, which are not conducive to plant succession. In this study, we studied the above-ground biomass and the degree of soil water storage deficit at different alfalfa stands of different planting ages. The experiment was conducted in six alfalfa grasslands of different ages. Soil water content of the 0–300 cm soil layer in each grassland was measured for the calculation of soil water storage deficit. The results showed that soil water storage increased gradually along the soil profile. The degree of soil water storage deficit was the highest in all six alfalfa grasslands at the depth of 0–150 cm. The deficit degree of the one- and six-year-old alfalfa grasslands was significantly higher than that at the grasslands that had been cultivated for two to five years (P < 0.05) at the depth of 0–100 cm. The deficit degree of the four- and five-year-old alfalfa stands was less than 10% below the depth of 200 cm. The above-ground biomass reached a peak value in grasslands that had been cultivated for three and four years, and then gradually decreased. In summary, based on its relatively high yield and low soil water consumption intensity, the optimal cultivation age for alfalfa grasslands was four years. Thus, irrigation should be increased after five years’ cultivation of alfalfa. Moreover, more water should be supplied to the upper soil layer of one-year-old alfalfa grassland stands. This study provides the basis for water management measures of alfalfa grasslands in arid areas.

Stand age affects emissions of N2O in flood-irrigated alfalfa: a comparison of field measurements, DNDC model simulations and IPCC Tier 1 estimates

Predicting N2O emissions in perennial legume systems, such as alfalfa (Medicago sativa), is challenging due to the uncertainty regarding the interaction of biologically fixed nitrogen (N) with carbon sources, soil properties, and management factors. We measured alfalfa yields, N2O fluxes, and soil variables in adjacent flood-irrigated commercial fields with 2nd and 5th year stands of alfalfa planted in clay soil in California during one year. Cumulative annual N2O emissions from the 5th year alfalfa stand were 5.26 (±0.55 standard error) kg N2O–N ha−1 and more than twice as large as those in the adjacent 2nd year stand, which were 2.26 (±0.25) kg N2O–N ha−1. Annual yields of the 5th and 2nd year alfalfa stands were 12.1 and 14.1 Mg dry matter ha−1, respectively. Annual emissions calculated according to current Intergovernmental Panel on Climate Change (IPCC 2006) methodology underestimated emissions by 74% (2nd year stand) and 90% (5th year stand), which highlights the limitation of estimating N2O emissions based solely on the biomass N inputs incorporated into the soil. The DeNitrification-DeComposition (DNDC) model, using as inputs soil properties, water inputs, yield potential, and climate data accurately predicted cumulative annual N2O emissions from both the 5th year (5.6 kg N2O–N ha−1) and the 2nd year (2.2 kg N2O–N ha−1) alfalfa stands, although there were discrepancies between measured and modeled daily flux values. The potential accumulation and mineralization of organic matter as a result of alfalfa root turnover is the most likely explanation for the increase in N2O emissions with stand age.

Forage yield, soil water depletion, shoot nitrogen and phosphorus uptake and concentration, of young and old stands of alfalfa in response to nitrogen and phosphorus fertilisation in a semiarid environment

Alfalfa (Medicago sativa L.) is an important forage legume in crop–pasture and animal husbandry systems in the semiarid Loess Plateau of China, but comprehensive studies on forage yield, shoot N and P relationships, and soil water use as affected by nitrogen (N) and phosphorus (P) fertility levels are scarce. The objective of this study was to assess the yield response of alfalfa stands of different ages following N and P fertiliser application in relation to water use in the semiarid region of the Loess Plateau. Field experiments were conducted from 2011 to 2014 in newly-established (young) and well-established (old) rainfed alfalfa stands, planted in 2010 and 2005, respectively, on the semiarid Loess Plateau. Treatments were a factorial combination of two N rates (0 and 70kgNha−1) and three P rates (0, 17 and 34kgPha−1), applied annually, arranged in a randomized complete block design with three replicates. Forage biomass was measured in mid-July and mid-October each year. The forage yield of the two alfalfa stands increased with N and P fertilisation, but path analysis indicated that it was also affected by rainfall. Water use was greater in the young than the old stand. The water content in the 1–4m soil layer of the young stand decreased each year from establishment; greater water depletion occurred with N and P fertilisation. In the five-year-old stand, the soil water content changed little over the four growing seasons, and N and P fertilisation did not affect the already depleted soil water content. Shoot P concentration was weakly, but positively, associated with shoot N concentration. The risk of low relative forage yield was greater when the shoot N:P ratio was more than 17. We conclude that N and P fertilisation, particularly P fertilisation, increases forage yield in both young and old rainfed alfalfa stands in a semiarid environment.

Persistence of Alfalfa Sod‐Seeded into Bermudagrass Pastures on Coastal Plain Soils

Alfalfa (Medicago sativa L.) production and persistence in the Lower South of the USA are dependent on climate, soil, and competition from warm‐season perennial grasses such as bermudagrass [Cynodon dactylon (L.) Pers.]. A 3‐year study was conducted at Texas A&amp;M AgriLife Research, Overton, to evaluate ‘Alfagraze’ alfalfa persistence on a Darco loamy fine sand (loamy, siliceous thermic Grossarenic Paleudult) when sod‐seeded at three row spacings (10, 20, and 30 inches) into a well‐established ‘Coastal’ bermudagrass pasture. Alfagraze was rotationally stocked with animal residence time from 5 to 13 d and deferment periods ranging from 18 to 27 d. In Year 1, during the first three grazing periods (1 April to 31 May), alfalfa was the dominant species (P &lt; 0.05). Thereafter, from 30 June to 3 October, bermudagrass was dominant (P &lt; 0.05). At the initiation of harvest in Year 2 (1 April), alfalfa dry matter (DM) was 1353, 783, and 690 lb/acre, respectively, at 10‐, 20‐, and 30‐inch drill‐row spacing prior to bermudagrass growth. At the end of Year 2 (3 October), alfalfa DM was 33, 10, and 0.90 lb/acre, respectively, at 10‐, 20‐, and 30‐inch spacings while bermudagrass DM was 1424, 1557, and 1080 lb/acre. At the beginning of Year 3, the percent stands of alfalfa were 14, 11, and 5%, respectively, for 10‐, 20‐, and 30‐inch spaced alfalfa plantings, while the respective percent stands of bermudagrass were 86, 89, and 95%. Under the climatic and sandy Coastal Plains soils of this vegetation region, Alfagraze was not persistent under grazing at any row spacing for more than 3 years when sod‐seeded into a well‐established Coastal bermudagrass pasture.

Application of local binary patterns in digital images to estimate botanical composition in mixed alfalfa–grass fields

Botanical composition in mixed stands of alfalfa and grass is a critical parameter in equations estimating harvest fiber concentration for dairy rations. Composition is difficult to estimate by visual observation. Digital image analysis in mixed stands could reduce botanical composition uncertainty and improve spring harvest management decisions. Mixed stands were sampled (n=168) in farmers’ fields in Tompkins County, New York in May 2011. A digital image was taken of standing samples at 5-Megapixels resolution using a Canon PowerShot A3100IS, and alfalfa and grass height relationships were recorded. After clipping representative samples at 10-cm above ground level, samples were manually separated into alfalfa (Medicago sativa L.) and timothy grass (Phleum pratense L.), and dried to calculate fractions on a dry matter basis. Uniform rotation invariant local binary patterns (LBP) were extracted from whole images and 64×64pixel tiles, and were used to develop regression equations estimating grass fraction. Tiles were manually classified as alfalfa (0), grass (1) or unclassifiable. An iterative process selected most accurate local binary pattern operator settings. Grass fraction was estimated in three regression model development approaches: (1) using average tile LBP histogram bins from whole images and botanical height relationships, (2) developing a binary tile classification model from tile LBP histogram bins, and using tile model-predicted grass probability averaged for tiles in whole images (grass coverage estimate) and botanical height relationships as inputs in whole image models, and (3) using LBP histogram bins extracted directly from whole images (1024 by 1024pixel square) and height relationships. Predictive accuracy in whole image models using tile LBP histogram averages was highest for models generated from LBP tile histogram bin means (R2pred up to 0.847), followed closely by combined tile models and whole image models (R2pred up to 0.807), with pairwise correlations between tile model-generated grass coverage estimates and sample grass fraction up to 0.895. Local binary patterns are effective in differentiating alfalfa and grass under field conditions, because the method is robust to changes in color and illumination. Furthermore, key LBP histogram bins (e.g., symmetric edges) strongly differentiate alfalfa and grass in tiles. The LBP method is promising based on this study, but further evaluation under diverse field conditions, including different cameras and grass species, is necessary to assess usefulness.

Prohexadione–Calcium Improves Stand Density and Yield of Alfalfa Interseeded into Silage Corn

Interseeded alfalfa (Medicago sativa L.) could serve as a dual‐purpose crop to provide groundcover for silage corn (Zea mays L.) and forage during subsequent years of production, but interspecific competition often leads to poor stands of alfalfa and unsatisfactory yields of corn. Four experiments evaluated whether interspecific competition could be alleviated by application of plant growth retardants (PGRs) on alfalfa interseeded at corn planting. In three experiments, foliar application of prohexadione‐calcium (PHD) on seedlings approximately doubled stand density of interseeded alfalfa during establishment in corn and following 1 yr of alfalfa forage production. Untimely PHD application in one experiment, however, failed to prevent stand failure of alfalfa growing under warm and damp conditions that favored vigorous growth of corn. When successfully established without PHD, average dry matter yield (DMY) of interseeded alfalfa the year following corn was 85% greater than conventionally spring‐seeded alfalfa; prior year PHD application further increased DMY of interseeded alfalfa by 15%. When tested with PHD in two experiments, seed soaking or coating with uniconazole (UCZ) or paclobutrazol (PBZ) reduced stand density and had neutral or adverse impacts on DMY of alfalfa following corn. Interseeding reduced silage corn DMY by an average of 10% compared to monoculture corn and PGR treatment of alfalfa usually failed to alleviate yield depression in corn. Overall, PHD shows promise for enhancing the establishment and subsequent yield of interseeded alfalfa, but further work is needed to refine this production system for farm use.Core Ideas Interseeded alfalfa can serve as a cover and forage crop Interseeding alfalfa in corn can double first year yields of alfalfa Prohexadione doubles seedling survival of interseeded alfalfa Prohexadione increases first year yield of interseeded alfalfa Prohexadione does not alleviate corn yield depression due to interseeding

Direct undersowing of degraded stands with annual and perennial legumes in the Northern Bulgaria

The possibility of annual and perennial legume crops to be used for undersowing of degraded pasture stands and alfalfa seed production stands was studied in the conditions of the Northern Bulgaria. The direct undersowing of degraded pasture stands was done after harvest with these legumes: birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifoliumpratense L.), black medick (Medicago lupulina L.), arrowleaf clover (Trifolium vesiculosum Savi), and common vetch (Vicia sativa L.). The undersowing of degraded seed production stands of alfalfa was done in autumn of the fourth year of using with subterranean clover (Tr. subterraneum ssp. brachycalicinum cv. Antas). Red clover showed the best results in terms of suitability for the direct undersowing of degraded pasture stands. Subterranean clover could be used for the direct undersowing of the degraded alfalfa seed production stands due to its self-seeding ability.

Alfalfa Stand Length and Subsequent Crop Patterns in the Upper Midwestern United States

Alfalfa (Medicago sativa L.) can provide many economic and environmental benefits to crop rotations. Our objectives were to quantify alfalfa stand lengths, identify the two crops following alfalfa, and determine the soil and temporal factors affecting them. The USDA‐National Agricultural Statistics Service (NASS) Cropland Data Layers (CDLs) for 2006 to 2012 and USDA‐NRCS soil survey layers for North Dakota, South Dakota, Nebraska, Minnesota, Iowa, and Wisconsin were combined and used to meet these objectives. Location and soil textural class generally determined stand length, with alfalfa being kept in production longer outside the major Corn Belt area of this region. Soil textural class effects on stand length varied by state. Corn (Zea mays L.) was the most common crop planted during the first‐ and second‐year following alfalfa (79 and 61%, respectively), except in North Dakota (35% both years). Soybean [Glycine max (L.) Merr.] was grown in 11 and 28% of cases, respectively. Small grains were planted as the first‐year crop in 29% of cases in the Dakotas and 6% of cases in the other four states. As a second‐year crop, small grains occurred in 26% of cases in North Dakota and 5% of cases in the other five states. Stand length, soil textural class, state, and year significantly influenced grower choice of both following crops. These geographic assessments will guide research and extension education designed to increase use of perennials for economic and environmental benefits. Similar methods can be applied to other crop rotations or U.S. regions.