Increased Forage Yield Research Articles

Effect of planting density on yield, nutritional quality, and ruminal in vitro digestibility of corn for silage grown under on-farm conditions

The objective of this on-farm study was to determine the effect of planting density on yield, nutritional composition, and fiber digestibility of corn silage. This study was performed during the spring and summer seasons of 2014 and 2015 at 2 commercial dairy farms located in Virginia. The study included 7 cornfields with different growing and harvesting conditions. In each cornfield, corn was planted in plots at a theoretical seeding rate of 55,000, 70,000, 85,000, and 100,000 seeds/ha (55K, 70K, 85K, and 100K, respectively). Each seeding rate had 4 replicates within each cornfield. The preceding crop was annual ryegrass that was harvested for silage within 10 d before planting corn. Plant DM biomass decreased linearly (376 vs. 253 g of DM/plant for 55K and 100K, respectively; P < 0.01), but DM yield increased linearly (19.8 vs. 26.0 Mg/ha for 55K and 100K, respectively; P < 0.01) when planting density increased. The number of kernels per ear and the stem width decreased proportionally as corn population density increased. Planting density did not affect, or minimally affected, the concentrations of ash, CP, NDF, ADF, ADL, starch, and sugar of fresh corn and corn silage. Also, planting density did not affect ruminal in vitro NDF digestibility of fresh corn and corn silage. In conclusion, increasing corn planting density increased forage yield when planted in a double-cropping system, minimally affecting nutritional quality and ruminal in vitro digestibility of corn silage.

Effect of Fungal Endophytes on Biomass Yield, Nutritive Value and Accumulation of Minerals in Ornithopus compressus.

Yellow serradella (Ornithopus compressus), a valuable pasture species in Mediterranean areas, presents a high diversity of endophytic mycoflora. In the present work, the hypothesis of a significant effect of fungal endophytic species on the parameters of forage production, nutritive value and mineral status of herbage was tested. O. compressus plants were inoculated with each of seven endophytes (four in 2012/2013 and three in 2013/2014). After inoculation, two experiments (under greenhouse and field conditions) were established. Results evidenced a certain influence of several endophytes on herbage yield, nutritive value and mineral status of O. compressus forage. Byssochlamys spectabilis increased herbage biomass yield by around 42% in the field experiment. Stemphylium sp. improved the nutritive value of forage either by increasing crude protein, digestibility and the concentration of essential minerals (such as B, Mo, P or S) or by reducing the concentration of toxic elements such as Al or Pb. In conclusion, the results presented here provide evidence that plant inoculation with endophytes could be a suitable strategy to increase forage yield and its nutritive value or to deal with potential nutrient deficiencies or potential mineral toxicity in forage.

Net effects of nitrogen fertilization on the nutritive value and digestibility of oat forages

Applications of soil amendments containing N are part of routine forage-management strategies for grasses, with a primary goal of increasing forage yield. However, the effects of N fertilization on forage nutritive value, estimates of energy density, and in vitro dry matter or neutral detergent fiber disappearance sometimes have been erratic or inconsistent. Our objectives were to evaluate the effects of N fertilization on the nutritive value of a single cultivar (ForagePlus, Kratz Farms, Slinger, WI) of fall-grown oat fertilized at planting with 20, 40, 60, 80, or 100 kg of N/ha of urea or 2 rates of dairy slurry (42,300 or 84,600 L/ha). Nitrogen fertilization exhibited consistent effects on fiber components; forages fertilized with urea or dairy slurry had greater concentrations of fiber components compared with those harvested from unfertilized check plots (0 kg of N/ha), and fiber concentrations increased linearly with urea fertilization rate. In contrast, concentrations of water-soluble carbohydrates were greatest for unfertilized forages (21.2%), but declined linearly with urea fertilization, exhibiting a minimum of 13.5% at the 80 kg of N/ha urea application rate. Similarly, nonfiber carbohydrates also declined linearly, from 34.8% for unfertilized check plots to a minimum of 24.6% at the 80 kg of N/ha urea application rate. Fertilization with urea resulted in consistent linear increases in crude protein (CP), neutral detergent soluble CP, neutral detergent insoluble CP, and acid detergent insoluble CP; however, the partitioning of CP on the basis of association with specific fiber fractions could not be related to N fertilization when concentrations were expressed on a percentage of CP basis. The summative calculation of energy, expressed as total digestible nutrients was closely related to N fertilization rate during both the 2013 (y = -0.038x + 72.2; R2 = 0.961) and 2014 (y = -0.040x + 69.2; R2 = 0.771) production years. Following 30- or 48-h incubations in buffered rumen fluid, in vitro dry matter disappearance was greater for unfertilized forages compared with those fertilized with either urea or dairy slurry, and disappearance declined linearly with urea fertilization rate; however, these responses were not detected for neutral detergent fiber disappearance. Overall, the forage nutritive value of fall-grown oat declined mildly in response to N fertilization, but these responses were not nearly strong enough to offset the advantages obtained by improved forage yields.

Intensification, nitrogen use and recovery in grazing-based dairy systems

There is increased international interest in the intensification of grazing-based dairy systems such as those that occur in Australia. However, associated with increased milk production on a per ha basis is the potential for decreasing nitrogen (N) recovery and increased N losses to the environment. In this study we produced a 22-year (1990–2012) time series of N recovery measures, for the entire Australian dairy industry and largest dairy producing State, Victoria, using a farm-gate N balance method and long-term farm survey data. Nitrogen recovery measures included whole-farm N surplus (kgNha–1), N use efficiency (%), milk production N surplus (gNl–1 milk) and total industry-wide N surplus (tN). On-going intensification in dairy production at both the national and state level led to fewer and larger dairy farms, with increased stocking rates, reliance on imported feed, nitrogen fertiliser use and milk production per cow and per hectare. All N recovery measures deteriorated markedly over the 22year period, although the adverse trend moderated somewhat since 2006. The Victorian industry was higher-performing in terms of N recovery compared to the national dairy industry as a whole, though there was some convergence during the last decade. The whole-farm N surplus for the ‘industry’ average Australian dairy farm increased from 54 to 158kgNha–1 and 38 to 136kgNha–1 yr.–1 for the average Victorian dairy farm. Nitrogen use efficiency declined from 40 to 26% and from 51 to 29% for the average Australian and Victorian farm, respectively. Milk production N surplus increased from 10.2 to 17.3 (Australian farm) and 6.9 to 15.2gNl–1 milk (Victorian farm). Total N surplus increased from 63,076 to 164,621tN for the Australian dairy industry as a whole, despite a decline of 470,000ha in land used in dairying, suggesting a growing problem in terms of higher losses of reactive N. Looking to the future, we examined a scenario whereby N use efficiency for Victorian dairy farms increases to 35% by 2030 due to higher milk yields per cow and per hectare, increased forage yields, improved bovine genetics and feed conversion efficiencies. Given the trends over 22years and currentN use efficiency, this goal will be difficult to achieve within current grazing-based dairy farming operations. Improvements in N recovery will likely depend on significant on-farm mitigation incentivised by cost-effective policy measures, as well as future technological advances stemming from strong public and industry investment in research and development.

The Impact of Harvest Timing on Biomass Yield from Native Warm‐Season Grass Mixtures

Interest in using native warm‐season grasses (NWSG), especially switchgrass (SG) (Panicum virgatum L.), as a biomass crop has increased due to the focus on renewable energy sources. There is the potential to utilize the early growth of these plants as a forage crop (i.e., hay), allowing the regrowth to be harvested as a fibrous biomass crop. The three species treatments were SG, a two‐way blend of big bluestem (Andropogon gerardii V.) and indiangrass (Sorghastrum nutans L.) (BB+IG), and a three‐way mixture of SG, BB, and IG (SG+BB+IG). Harvest treatments were a harvest (BH) in late fall (for biomass), early‐boot harvest (for forage) followed by BH (EB+BH), or early‐seedhead harvest (for forage) followed by BH (ESH+BH). Delaying harvest from EB to ESH increased forage yield by 22% (P &lt; 0.001). The SG and SG+BB+IG produced greater forage yield (averaged across both early harvest treatments) than BB+IG (10.1 and 9.1 vs. 5.5 Mg DM ha−1, respectively; P &lt; 0.001). Across all NWSG treatments, biomass yield was reduced by 51% for EB+BH and 68% for ESH+BH compared to BH (P &lt; 0.001). Total yield (forage + biomass) was greatest for ESH+BH with both SG and SG+BB+IG, whereas the mixture of SG+BB+IG provided the greatest total annual yield, 20.1 Mg DM ha−1 (P = 0.002). These results suggested that NWSG, grown in the mid‐South United States under a dual‐harvest system, can increase harvest options for producers by supplying acceptable forage yield for both early harvests and still provide biomass production.

Yield and Quality of Forage Oat (&amp;lt;i&amp;gt;Avena sativa&amp;lt;/i&amp;gt; L.) Cultivars as Affected by Seed Inoculation with Nitrogenous Strains

Nitrogen availability can be enhanced with the application of nitrogen fixing bacteria and it may be helpful in increasing forage yield and improving quality of oat. Therefore, a field trial to evaluate the effect of seed inoculation with nitrogen fixing bacteria on forage yield and quality of oat was carried out at Agronomic Research Area, University of Agriculture, Faisalabad during Rabi season 2013-14. The experiment was laid out in Randomized Complete Block Design (RCBD) with factorial arrangements using three replications. The experiment was comprised of two integrated approaches. The first approach was oat cultivars consisting of four treatments, V1 (AVON), V2 (S-2000), V3 (S-2011) and V4 (PD2LV65) and the second approach was seed inoculation consisting of three treatments, S0 (control), S1 (Azotobacter spp.), S2 (Azospirillum spp.). Fisher’s analysis of variance technique was used for statistically interpretation of data by using least significant difference (LSD) test at 5% level of probability. Nitrogen fixing bacteria significantly affect the germination count (m2), plant height (cm), number of tillers (m2), number of leaves per tiller, leaf area per tiller (cm2), green forage yield (t·ha-1) and dry matter yield (t ha-1). The maximum green forage yield (85.2 t·ha-1), dry matter yield (14.1 t ·ha-1) and crude protein (11.5%) were recorded where Azotobacter inoculation was applied. The interaction between cultivars and nitrogenous strains was significant for green forage yield (t·ha-1), dry matter yield (t·ha-1) and crude protein (%). Conclusion showed that cultivar Sargodha-2011 which was inoculated with Azotobacter spp. gave higher forage yield of good quality.

Genetic Variation for Dry Matter Yield, Forage Quality, and Seed Traits Among the Half‐Sib Progeny of Nine Orchardgrass Germplasm Populations

ABSTRACTA potential strategy to address the lack of success of North American orchardgrass (Dactylis glomerata L.) breeding programs to increase forage yield and other agronomic traits is the incorporation of novel sources of germplasm. In an attempt to identify novel orchardgrass germplasm sources with agronomic potential, the study described herein characterized 162 half‐sib families (HSFs) from six orchardgrass germplasm populations and three orchardgrass cultivars. Study conditions were Millville, UT, and Rexburg, ID, field sites with data collection from 2008 to 2010. The genotype × location interaction variance differed from zero for dry matter yield, crude protein, in vitro true digestibility (IVTD), neutral detergent fiber, and seed weight. Within location broad‐sense heritability differed for all traits at both locations (0.36 ±0.10 to 0.77 ±0.03) except IVTD at Rexburg. For each trait there were HSFs that possessed values similar to or better than the included check cultivars (CCs). Additionally, in several instances the mean phenotype of the HSFs from a specific family was better than the phenotype of the corresponding parental population and/or the mean phenotype of the CCs. Overall, for each trait there existed sufficient genetic variation to develop an elite orchardgrass breeding program for irrigated conditions.

Yield and Quality Response of Ryegrass, Egyptian Clover and Their Mixtures to Different Sources of Fertilizers

Two field experiments were conducted during two successive winter seasons of 2008/2009 and 2009/2010 to investigate the potentialities of mixing Egyptian clover with ryegrass under bio, organic and mineral fertilization treatments and their combination to increase forage yield and quality grown under sandy soil conditions. The experiment included the combination of five mixing ratios (Egyptian clover alone, ryegrass alone, 75% Egyptian clover: 25% ryegrass, 50% Egyptian clover: 50% ryegrass and 25% Egyptian clover: 75% ryegrass) and eight fertilizer sources, which include control, organic fertilization, bio fertilization, chemical fertilizer, organic + bio fertilizer, organic + chemical fertilizer, bio + chemical fertilizer and combination of organic and chemical and bio fertilizers. The obtained results indicate the superiority of 75% E. clover: 25% ryegrass mixture fertilizedby Bio + O + N in fresh and dry forage production. On the other hand, it reported the lowest dry weight of weeds g/m2. Chemical analysis of forage plants showed that the mixture of 75% E. clover: 25% ryegrass surpassed that of other treatments yield for crude protein, ether extract and ash. The results also revealed that the highest record of DCP, crude fiber and TDNY was obtained by forage mixture of 75% E. clover: 25% ryegrass fertilized with Bio + O + N. Such higher yield of these characters hassecured a balanced ratio which is really needed for ruminants ration.

Plant assemblage composition and soil P concentration differentially affect communities of AM and total fungi in a semi-arid grassland.

Adding inorganic P- and N-fixing legumes to semi-arid grasslands can increase forage yield, but soil nutrient concentrations and plant cover may also interact to modify soil fungal populations, impacting short- and long-term forage production. We tested the effect of plant assemblage (seven native grasses, seven native grasses + the domesticated N-fixing legume Medicago sativa, seven native grasses + the native N-fixing legume Dalea purpurea or the introduced grass Bromus biebersteinii + M. sativa) and soil P concentration (addition of 0 or 200 P2O5 kg ha(-1) at sowing) on the diversity and community structure of arbuscular mycorrhizal (AM) fungi and total fungi over two consecutive years, using 454-pyrosequencing of 18S rDNA and ITS amplicons. Treatment effects were stronger in the wet year (2008) than the dry year (2009). The presence of an N-fixing legume with native grasses generally increased AM fungal diversity, while the interaction between soil P concentration and plant assemblage modified total fungal community structure in 2008. Excluding interannual variations, which are likely driven by moisture and plant productivity, AM fungal communities in semi-arid grasslands appear to be primarily affected by plant assemblage composition, while the composition of other fungi is more closely linked to soil P.

The effect of row spacing on alfalfa seed and forage production under irrigated Mediterranean agricultural conditions

AbstractWe evaluated the effect of row spacing on seed and forage yields in alfalfa (Medicago sativa L.) using combined seed and forage production plots, in an irrigated Mediterranean agricultural environment. We compared three row distances (20, 40 and 60 cm) in two cultivars at a seed rate of 25 kg ha−1 over a period of 4 years. We measured the seed yield and yield components as well as forage production. The 4‐year average revealed an overall clean seed yield of 367 kg ha−1 declining over time, without significant differences in row distances. The number of shoots per square metre differed significantly as a function of row spacing, with averages of 357, 226 and 172 shoots m−2 for row widths of 20, 40 and 60 cm respectively. The row spacing did not affect the number of racemes per shoot (23·1), the number of pods per raceme (7·2), the number of seeds per pod (6·5) or the thousand seed weight (1·667 g). The average forage production was 20·1, 18·5 and 17·9 Mg DM ha−1 for row distances of 20, 40 and 60 cm, respectively, with higher yields associated with smaller row distances. Our data demonstrate that row spacing &gt;20 cm does not confer any advantage to the production of alfalfa seed under irrigated Mediterranean agricultural conditions and that close spacing can significantly increase forage yields in the same environment.

Long‐Term Runoff Water Quality as Affected by Broiler‐Litter Application to a Udult in the Ozark Highlands

Repeated annual land application of organic soil amendments, such as broiler litter (BL), to managed grasslands for increased forage yields has increased concerns about potential surface water contamination from runoff. Furthermore, water quality concerns are exacerbated in areas of underlying karst, such as the Ozark Highlands, where runoff can rapidly enter the groundwater system. Therefore, the objective of this study was to determine 8‐yr (May 2003–April 2011) linear trends in annual runoff water quality from a silt loam soil in the Ozark Highlands region of northwest Arkansas under natural precipitation and typical forage management amended annually with BL at three application rates (0 [control], 5.6 [low], and 11.2 [high] Mg BL ha−1) with a history of BL amendments and high soil‐test P. Average annual runoff, flow‐weighted mean (FWM) runoff concentrations of Ca, Cd, Cu, Na, and Se, and all nutrient and metal losses increased with time (P &lt; 0.05) but were unaffected (P &gt; 0.05) by BL application rate. Average annual FWM concentrations of As decreased with time (P &lt; 0.05) and were unaffected by BL (P &gt; 0.05). Eight‐year cumulative runoff losses of Se exceeded 200% of that applied in BL. Results indicated that pasturelands with a history of BL application and high soil‐test P may continue to release BL‐derived As and Se at concentrations potentially harmful to human and environmental health regardless of current management practice long after litter application has ceased.

Effect of applied cultivation technology and environmental conditions on lucerne farm yield in the Central Europe

The aim of this study was to investigate the impact of used technology and environmental condition on lucerne dry matter yield in the regional conditions. During a three year period (2011&amp;ndash;2013), the investigation was based on management survey in 27 farms in the Czech Republic. Climate conditions significantly influenced yield in some interaction with soil where only combination of dry climate and less fertile soil conditions reduced forage yield. The single soil effect was not significant for forage yield. Applied technology was influenced by both environment and farm characteristic (such as farm size and cow&amp;rsquo;s milk performance) which together significantly explained about 40% of variability of used technological properties. From all investigated technological properties, only cultivation of lucerne in mixture with grasses consistently increased forage yield therefore should be considered as important factor for modelling forage farm yield in the regional conditions.

남부지역 논에서 사료맥류-사료용 옥수수-하파귀리 삼모작 시 조사료 생산성 및 사료가치

Multiple cropping system is an important agricultural system in Korea, which is significant to increase forage yield and promote agricultural economic development. This experiment was carried out to develop triple cropping systems (winter cereals crop for forage - silage corn - summer oats) for maximum year-around forage production at paddy field in southern region. We also to select a winter forage crop to determine corn planting time, and to examine the forage productivity and feed value of summer cultivated oat, which was planted after corn cultivation. When winter cereal crops for forages are harvested in accordance with and corn planter, the fresh yield and dry matter yield of rye were 32.0 ton/ha and 5.8 ton/ha, respectively, showing higher yielding compared to other winter crops. Corn silage as summer crop was showed the fresh yield and dry matter yield of 72.1 ton/ha and 20.2 ton/ha, respectively. In the feed value, crude protein and TDN contents were 7.4% and 69.3%, respectively. They was showed higher productivity and feed value. The heading date of High-speed oat was October 10, and its fresh yield and dry matter yield were 37.6 ton/ha and 8.0 ton/ha, respectively. As a feed value, crude protein and TDN content was 11.4% and 59.1%, respectively. Therefore, triple cropping systems for the production of forage all throughout the year are possible with the introduction of summer oats in the southern region, and rye could be the most suitable winter forage crops for triple cropping systems.

Detection of QTL for forage yield, lodging resistance and spring vigor traits in alfalfa (Medicago sativa L.)

Alfalfa (Medicago sativa L.) is an internationally significant forage crop. Forage yield, lodging resistance and spring vigor are important agronomic traits conditioned by quantitative genetic and environmental effects. The objective of this study was to identify quantitative trait loci (QTL) and molecular markers associated with increased forage yield, resistance to lodging, and spring vigor. A backcross population composed of 128 progeny was developed by crossing the breeding parents DW000577 (lodging susceptible) and NL002724 (lodging-resistant) and back-crossing an individual F1 plant to the maternal parent (i.e. DW000577). A linkage map of NL002724 was developed based upon the segregation of 236 AFLP, SRAP, and SSR markers among the backcross progeny. The markers were distributed among 14 linkage groups, covering an estimated recombination distance of 1497.6 centiMorgans (cM). Replicated clones of both parents and backcross progeny were evaluated in the field for estimated forage yield, lodging, and spring vigor in Washington and Wisconsin during 2007 and 2008. Significant QTL were found for all three traits. In particular, two QTL for lodging resistance were identified that explained ≥14 % of trait variation, and were significant in all years and locations. Major QTL explaining over 25 % of trait variation for forage yield were detected in multiple environments at two separate locations on chromosome III. Several QTL for spring vigor were located in the same or similar positions as QTL for forage yield, possibly explaining the significant correlation between these traits. Molecular markers associated with the aforementioned QTL were also identified.

Forage yield of simple and complex grass–legume mixtures under two management strategies

Foster, A., Vera, C. L., Malhi, S. S. and Clarke, F. R. 2014. Forage yield of simple and complex grass–legume mixtures under two management strategies. Can. J. Plant Sci. 94: 41–50. Limited information is available on the dry matter production, protein content and species composition of complex mixtures of introduced perennial forage crop species for hay and pasture in the moister regions of Saskatchewan. A field experiment was sown on 2008 May 27 at Melfort, Saskatchewan, Canada, on a thick Black Chernozem (Udic Boroll) silty clay soil, to compare the effects on dry matter yield (DMY), protein content and species composition of perennial forage crop monocultures and mixtures, under a two-cut and a three-cut management system, in 2009, 2010, 2011 and 2012. Eleven treatments consisted of monocultures of hybrid bromegrass (Bromus riparius Rehm.×Bromus inermis Leyss.), smooth bromegrass (Bromus inermis Leyss.), crested wheatgrass [Agropyron cristatum (L.) Gaertn], intermediate wheatgrass [Agropyron intermedium (Host.) Beauv.] and alfalfa (Medicago sativa L.); simple mixtures of each of these individual grass species with alfalfa; a more complex mixture of all these grass species and alfalfa, and a very complex mixture consisting of the complex mixture plus meadow bromegrass (Bromus riparius Rehm.), orchardgrass (Dactylis glomerata L.), tall fescue [Festuca arundinacea (Schreb.) Wimm.], timothy (Phleum pratense L.) and slender wheatgrass [Elymus trachycaulus (Link) Gould ex Shinners]. The alfalfa was inoculated with rhizobium, and no fertilizer was added to any treatment during the course of the study. The two-cut system yielded higher than the three-cut system in all years. In 2009, the first cutting year, all treatments, especially under the two-cut system, produced similar forage DMY, with monoculture grasses yielding as much as that of their mixture with alfalfa. In 2010, 2011 and 2012, however, monoculture alfalfa and grass–alfalfa treatments had higher DMY than the monoculture grasses. Monoculture alfalfa also showed superior DMY than most grass–alfalfa mixtures, especially during the last 2 yr of the study. In conclusion, the inclusion of alfalfa in forage mixtures, grown in unfertilized soil, significantly increased forage yield, especially after the first production year, and these grass–alfalfa mixtures yielded almost as much as monoculture alfalfa. Also, the inclusion of alfalfa significantly increased the forage protein content over the grass alone treatments. Hybrid bromegrass, grown alone or in mixture with alfalfa, yielded similar to the other grasses tested, while crested wheatgrass did not compete as well as other main grasses, grown alone or in mixture with alfalfa. In this study, the use of complex or very complex mixtures of introduced grasses with alfalfa did not increase DMY over the simple grass–alfalfa mixtures.

Assessing Genotypic Diversity and Symbiotic Efficiency of Five Rhizobial Legume Interactions Under Cadium Stress for Soil Phytoremediation

In the framework of soil phytoremediation using local legume plants coupled with their native root-nodulating bacteria to increase forage yields and preserve contaminated soils in arid regions of Tunisia, we investigated the diversity of bacteria from root nodules of Lathyrus sativus, Lens culinaris, Medicago marina, M. truncatula, and M. minima and the symbiotic efficiency of these five legume symbiosis under Cadmium stress. Fifty bacterial strains were characterized using physiological and biochemical features such heavy metals resistant, and PCR-RFLP of 16S rDNA. Taxonomically, the isolates nodulating L. sativus, and L. culinaris are species within the genera Rhizobium and the ones associated to Medicago sp, within the genera Sinorhizobium. The results revealed also that the cadmium tolerance of the different legumes-rhizobia interaction was as follows: M. minima<M. truncatula<M. marina<L. sativus<L. culinaris indicating that the effect of Cadmium on root nodulation and biomass production is more deleterious on M. minima-S. meliloti and M. truncatula-S. meliloti than in other symbiosis. Knowledge on genetic and functional diversity of M. marina, L. sativus and L. culinaris microsymbiotes is very useful for inoculant strain selection and can be selected to develop inoculants for soil phytoremediation.

Estimates of variance components and repeatability for total forage yield in rye: implications for breeding

AbstractCereal rye (Secale cereale L.) is an important forage crop in the USA for stocker cattle (Bos sp.) production, thus making forage yield an important breeding objective for the crop. However, little information is known about the repeatability for forage yield in this crop. The objectives of this research were to: (i) estimate variance components for forage yield from long‐term variety trials, (ii) estimate the repeatability for forage yield and (iii) relate this to breeding strategies for increased forage yield in rye. Trials were conducted over 14 years where 97 USA open‐pollinated varieties (OPVs) were evaluated. Repeatability ranged from 0.57 to 0.86 when the data were analysed by year for the 3 years with significant genotype main effects. Possible explanations for the lack of significant genotype main effects are discussed. Practical implications of these findings indicate that the development of improved cultivars with greater forage yield will require improved methods of selection based on family performance rather than the current methods based primarily on single plant visual selection.

Weeds – Friend or foe? Increasing forage yield and decreasing nitrate leaching on a corn forage farm infested by redroot pigweed

Various weed management methods have been tested without complete success and still represent a major nuisance often negatively effecting yields. Therefore, it may be time to change attitudes about weeds and view them as friends of the agroecosystem rather than as foes. For the first time, field experiments were conducted to introduce and evaluate the yield and quality of corn–redroot pigweed mixture forage in a semi-arid region of Iran during 2010 and 2011. A randomized complete block design with a split factorial arrangement of treatments in four replications was subjected to low irrigation and full irrigation regimes. Subplots consisted of a factorial combination of four N levels (0, 150, 300 and 450kgNha−1) and two forage mixtures (corn monoculture and corn–redroot pigweed mixture). When averaged over both years, N addition (from 0 to 450kgNha−1) increased corn forage yield by 74 and 42% under full and low irrigation regimes, respectively. The forage yield increased by 121 and 69% in the corn–pigweed mixture for comparable treatments. In corn monoculture, the minimum required forage protein (90gkg−1) occurred only where forage yields were lower than 10tha−1, whereas in the corn–pigweed mixture, all the treatments with 90gkg−1 protein produced yield more than 11tha−1. N enhancement (0–450kgha−1) increased nitrate leaching loss (NLL) by 158 and 107kgha−1 in corn monoculture and 100 and 55kgha−1 in the corn–pigweed mixture under full and low irrigation regimes, respectively. However, an alteration in the NLL trend in response to N application grew in both forage types, but the NLL severity was reduced in the corn pigweed mixture. The integration of redroot pigweed (a major weed species on summer crop farms) with corn, rather than its removal, could be recommended to ensure an acceptable forage yield/quality in a poor sandy soil while also reducing N leaching.

Phosphorus application and liming effects on forage production, floristic composition and soil chemical properties in the Campos biome, southern Brazil

AbstractStudies of responses of native and introduced grassland species to lime and phosphorus (P) applications could contribute to improved understanding of the potential production of South American natural grasslands. To determine the effect of applying lime and different P sources on forage production, diversity and floristic composition, and on soil chemical properties, a small‐plot experiment was conducted over 12 years in natural grassland oversown with Lolium multiflorum and Trifolium vesiculosum in the Campos of southern Brazil. In treatments with soluble phosphate application, dry‐matter (DM) yield in November 2008, after 164 d of winter and early spring growth, increased from 2·3 to 3·2 t ha−1. Differences in DM yield in March 2009, after 111 d of growth during late spring and early summer, were not significant. The DM yield in April 2010, after 419 d of growth, increased from 7·7 to 9·2 t ha−1 in the treatments with P, regardless of the P source. Increased forage yield during the slow growth period in winter was only possible with the introduction of winter‐growing species (L. multiflorum and T. vesiculosum) and soluble phosphate application. Assessment of annual forage yield showed that the effectiveness of Gafsa rock phosphate was equivalent to that of soluble phosphates in the long term. Soluble phosphates and liming modified the botanical composition of natural Campos grassland in the long term, but floristic diversity was not altered.

Integrated maize management options to improve forage yield and quality on smallholder farms in Kenya

Maize provides an important source of forage for the maize–dairy farmers in Kenya. However, due to small farm size, maize cannot supply all the feed needed for dairy cattle and forage is in short supply in the dry seasons. This paper examines practices to increase the health and use of maize and increase forage quality and quantity. The paper uses data from participatory on-farm research on cultural management practices of maize and on-station field trials in which plants were artificially infected with maize streak virus disease (MSVD) in the intensive maize–dairy production systems in central Kenya. Findings showed that smallholder farmers have deliberately changed the maize management practices by planting densely and systematically thinning the crop to obtain both fodder and grain. They perceived MSVD to have the greatest effect on forage yields and to be a difficult disease to control. Maize management trials showed that increasing plant density increased forage yields by up to 41% but decreased grain yields by up to 17% when specific thinning regimes were applied fairly late in the growth of the crop. However, grain yields were maintained when maize was planted at high density and then progressively thinned for forage during the growing season according to the crop situation or need for forage. The on-station research is the first study on the impacts of MSVD on maize forage and was carried out to increase production of forage during the wet seasons through use of resistant cultivars and agronomic interventions with a view to mitigating forage shortages during the dry seasons. MSVD infection was achieved with artificially infected leafhoppers (Cicadulina mbila (Naudé) (Hem.: Cicadellidae). In the 2001 short rainy season (SRS), early infection (14 days after crop emergence) reduced thinning yields by 43% in the susceptible cultivar, H511, compared to only 22% in a tolerant one, KH 521. Stover yields were reduced by 24% in H511 while there were no significant losses in KH 521. Interestingly, the local landrace, Gikuyu, was tolerant of MSVD in terms of grain yield but not thinnings. Forage from crops infected 35 and 56 days after crop emergence did not differ significantly from the uninfected controls. In the 2002 long and short rainy seasons, early infection with MSV again reduced thinning and stover yields whereas fertilizer and plant density did not significantly affect the influence of MSVD on either maize forage or grain yields. Use of tolerant cultivars provided insurance against forage and grain yield losses caused by early infection by MSV, but yield benefits varied with season. With respect to forage quality, MSVD had a beneficial effect on susceptible cultivars (H511 and H614) due to the higher crude protein (CP) and lower neutral detergent fibre (NDF) concentrations of infected material in the early stages of growth. However, the reduced yields due to MSVD negate any advantage of increase in CP in infected material of susceptible maize cultivars. Further, the benefit of breeding for high NDF concentrations as a defense mechanism against disease effects is disadvantageous to improving quality of maize forage.