Dry Matter Yield Response Research Articles

Biomass yield, crude protein yield and nitrogen use efficiency over nine years in annual and perennial cropping systems

Emerging biorefinery technologies can lead to new applications and new markets for various types of crop biomass. This may allow significant changes in agricultural production from crop rotations dominated by annual grain and seed crops towards annual or perennial cropping systems composed with the aims of higher biomass yield and environmental sustainability. In this study, we investigated 7 annual and 7 perennial cropping systems on a sandy loam soil, with large differences in N fertilization. Yield of dry matter (DM) and crude protein (CP) was measured over nine growing seasons from 2013 to 2021. A conventional four-year cash crop rotation with cereals and winter oil seed rape served as a reference and achieved mean annual yields of DM and CP of 10.5 and 0.85 Mg ha−1 y−1, respectively, across the nine years. Continuous maize and triticale had significantly higher DM and CP yields, with 57 and 15 % increases in DM yield compared to the reference crop rotation, respectively. Optimized four-year crop rotations with various annual crops including triticale, maize, beet, hemp or faba bean and various intermediate crops achieved 51–84 % and 42–78 % higher yield of DM and CP, respectively. Perennial cropping systems with festulolium and tall fescue with three or four harvests per year achieved 63–65 % higher DM yield and 192–200 % higher CP yield (2.47–2.55 Mg ha−1 y−1) compared to the cash crop rotation. Perennial cropping systems with miscanthus and willow had high DM but low CP yield. As a measure of nitrogen use efficiency, partial factor productivity of DM yield (PFPDM) and CP yield (PFPCP) were calculated, and both varied significantly between cropping systems, with highest PFPDM for M. × giganteus and willow (114–192 kg DM kg N−1) and lowest for festulolium and tall fescue (38–40 kg DM kg N−1). PFPCP was highest for the optimized crop rotations (6.88–7.94 kg CP kg N−1) and lowest for miscanthus (2.94–4.98 kg CP kg N−1). Across 12 of the cropping systems, which included both protein crops and lignocellulosic crops, there was a non-linear DM yield response to N fertilization rate with PFPDM decreasing from 134.9 to 37.2 kg DM kg N−1 when increasing the N rate from 50 to 500 kg ha−1 y−1. On the other hand, there was a linear CP yield response and, therefore, a constant PFPCP of 5.94 kg CP kg−1 N across N fertilization rates. The results clearly indicate that cropping systems can be modified to achieve higher DM and CP yields but also that choice of cropping system and optimal N fertilization may need adjustment depending on the use of the harvested biomass, the possibilities for biorefining into various components and products as well as the economic value of the components.

Does fall manure injection cause differential growth and forage nutritive value in small grains?

AbstractProducers utilizing fall manure injection have reported increased growth and greenness in small grains growing on the injection band compared to small grains growing between injection bands. To determine how producers utilizing fall manure injection in small grains should manage potential differential growth, 24 sites under fall manure injection were established. Soil samples were taken in‐band and between‐band 1 month after manure application and at silage harvest for soil NO3‐N. Small grain growth stage was assessed 1 month after planting and at silage harvest, while dry matter (DM) yield and forage nutritive value parameters were assessed at silage harvest. Soil NO3‐N was elevated in‐band compared to between‐band 1 month after manure application (p < 0.05); however, this did not persist until silage harvest. No differences in growth stage were observed 1 month after planting in 2021; however, growth stage means were consistently elevated in‐band in 2022, likely due to earlier planting dates in 2022 compared to 2021. Growth stage at harvest was the same in‐band and between‐band at each site. Small grain DM yield was only increased in‐band compared to between‐band in three of 24 sites. Two of the three sites planted with wheat (Triticum aestivum L.) showed significantly increased DM yield in‐band, suggesting DM yield response could be species dependent. No consistent differences in forage nutritive value parameters were observed. As no consistent differences in small grain DM yield and forage nutritive value were found at harvest, we recommend no changes to management practices for producers utilizing fall manure injection in small grains.

Modified TAL expression in rice plant regulates yield components and grain quality in a N-rate dependent manner

Context or problemHigher-yield and superior-quality rice are the major goals in rice breeding and nitrogen management. Genetic modification combined with optimal nitrogen (N) fertilization is expected to realize it. Objective or research questionModification in transaldolase (TAL) expression alters both the number and pattern of vascular bundles in rice plants, but its interactions with N rate remains unknown. MethodsWe employed three representative lines with different expression levels of TAL in the same genetic background (Wuyunjing 7, WT), and analyzed their responses in dry matter accumulation (DMA), carbohydrate transport, grain filling, yield, yield components, and grain quality under a wide range of N rate. ResultsIncreased expression of TAL (OE) promoted rice yield by producing more spikelets per panicle and higher 1000-grain weight, while decreased expression of TAL lowered the seed setting rate and grain weight significantly. Under a fixed N rate, when TAL expression was altered, the direct path coefficients of the seed setting rate and 1000-grain weight to the yield were higher than other yield components, especially at a high N rate. Decreased expression of TAL (RNAi) significantly reduced the starch and non-structural carbohydrates (NSC) contents in the stems, but enhanced the soluble sugar retention, whereas increased expression of TAL enhanced the translocation of NSC. The grain weight at maturity and mean grain-filling rate (mg d−1) increased significantly along with the TAL expression, but their differences among RNAi, WT and OE narrowed at higher N rate. Decreased expression of TAL enhanced the apparent amylose content (ACC) and protein (PC), reduced the starch granule size, and caused a loose starch arrangement and elevated chalkiness, as a consequence, significantly reduced the peak viscosity, hot viscosity, final viscosity, and taste value in a N rate dependent manner. The taste values of OE and WT were similar and the highest value was attained under a moderate N rate. ConclusionsTAL expression plays an important role in the regulation of assimilate supply, grain filling, yield formation, and grain quality. Increased expression of TAL alleviates competition effect among the yield components and enhances the yield potential, especially under moderate to high N rate. Higher TAL expression combined with a moderate N rate improves ECQ. Implications or significanceTAL expression and N rate interacts to regulate yield components and quality. This finding provides meaningful knowledge to administering N rate and genetically modifying TAL expression in a rice variety.

Incorporating Plantain with Perennial Ryegrass-White Clover in a Dairy Grazing System: Dry Matter Yield, Botanical Composition, and Nutritive Value Response to Sowing Rate, Plantain Content and Season

Incorporating plantain with perennial ryegrass and white clover (RGWC) can improve the quality and quantity of grazing pastures; however, the sowing rate could affect the persistence of plantain, pasture yield, and nutritive value in different seasons. The objective of this study was to evaluate the effect of increasing sowing rates of plantain when established with RGWC on the dry matter (DM) yield, botanical composition, nutritive value, and bioactive compounds of the pasture over the first two years after sowing; and to determine the relationship between plantain content and nutritive characteristics in different seasons. The pasture treatments were RGWC, RGWC + low plantain rate (PLL), RGWC + medium plantain rate (PLM), and RGWC + high plantain rate (PLH). The results showed that annual DM yield was similar between treatments. The average plantain content (including leaves and reproductive stem) was 32, 44, and 48% in PLL, PLM, and PLH, respectively. The plantain composition increased in the first 15 months, then declined rapidly to about 20–30% at day 705 after sowing. Compared with RGWC, the plantain-RGWC pastures (PLL, PLM, PLH) had a higher content of organic matter digestibility (OMD), ash, starch, non-structural carbohydrates (NSC), P, S, Ca, Mg, Na, Cl, Zn, B, Co, aucubin, acteoside, and catalpol, while they contained a lower composition of DM%, acid detergent fibre (ADF), neutral detergent fibre (NDF), crude fat (CF), Fe, and Mn. These differences were linearly associated with the content of plantain leaves in the pasture and were higher in summer and autumn than in spring. In conclusion, incorporating plantain into the RGWC pasture can improve herbage nutritive quality, thus potentially increasing farm productivity and environmental benefits. However, further work is required to investigate management interventions to sustain plantain content beyond two years from sowing.

Nitrogen and phosphorus fertilizer application to Elephant grass (<i>Cenchrus purpureus</i> syn. <i>Pennisetum purpureum</i>) cultivar ‘Cameroon’ in an arenosol in Rio Grande do Norte, Brazil

Elephant grass (Cenchrus purpureus syn. Pennisetum purpureum) stands out for its high dry matter production per unit area and good nutritional value and is cultivated throughout Brazil. This study aimed to evaluate the performance of elephant grass cultivar ‘Cameroon’ fertilized with nitrogen (N) and phosphorus (P) at different rates. The experimental design was in randomized blocks with 10 treatments and 4 replicates. The treatments consisted of 5 doses of N (0, 200, 400, 600 and 800 kg N/ha) all with 66 kg P/ha and 5 doses of P (0, 22, 44, 66 and 88 kg P/ha) all with 600 kg N/ha. The variables evaluated during 3 harvests were: shoot dry matter (DM) yield, N and P concentrations in shoots, and uptakes of N and P in forage. Results showed that, in the arenosol of the experimental area, high doses of N and P could produce high yields of the grass (40‒41 t DM/ha) over 260 days. The grass extracted large amounts of N (on average, 800 kg N/ha over 260 days) and P concentrations were significantly affected by P fertilization only in the last harvest, where it increased from 0.27 to 0.78 g P/kg DM. However, application of only 200 kg N/ha will produce more than 60% of the DM yield response achieved with 800 kg N/ha. Similarly, there seems little merit in applying more than 22 kg P/ha with the N. Longer-term studies are needed to test these hypotheses along with economic assessments to determine the financial soundness of such decisions.

Mineral fertiliser equivalent value of dairy processing sludge and derived biochar using ryegrass (Lolium perenne L.) and spring wheat (Triticumaestivum)

As supply chains of chemical fertilisers become more precarious, raw or derived bio-based fertilisers (herein referred to as bio-fertilisers) from the dairy processing industry could be good alternatives. However, their agronomic performance is relatively unknown, and where documented, the method to estimate this value is rarely presented. This pot study investigated aluminium-precipitated and calcium-precipitated dairy processing sludges (Al and Ca-DPS) and DPS-derived biochar as potential bio-fertilisers to grow ryegrass (Lolium perenne L.) and spring wheat (Triticum aestivum). The study aims were to examine how (1) application rate (optimal versus high) and (2) calculation methods (with and without chemical fertiliser response curves) can affect estimates of nitrogen and phosphorus mineral fertiliser equivalence value (N- and P-MFE) and associated agronomic advice. The results from both crops showed that for nitrogen application rates (125 or 160 kg ha−1 for ryegrass and 160 or 240 kg ha−1 for spring wheat) estimates of N-MFE increased for both Al-DPS and Ca-DPS as application rate increased. Dry matter yield response curves produced the highest % N-MFE results (e.g., ryegrass ∼50% and 70% for Al-DPS and Ca-DPS) with other calculation methods producing all similar results (e.g., ryegrass ∼20% for Al-DPS and Ca-DPS). For phosphorus application rates (40 or 80 kg ha−1 for ryegrass and 50 or 80 kg ha−1 for spring wheat), estimates of P-MFE did not increase with application rate. Negative P-MFE values obtained for Ca-DPS and DPS-biochar when growing ryegrass and spring wheat grain, respectively, indicated low plant available phosphorus. Overall, Al-DPS had better performance as a bio-fertiliser when compared to the other products tested. There was no significant difference between the two calculation methods of MFE, which suggests that the determination of MFE could be simplified by using one application as opposed to numerous application rates of fertilisers. Future work should focus on elucidating the N- and P-MFE of a wider range of DPS and STRUBIAS bio-fertilisers, and alternative methods should be investigated that enable a comparison across all bio-fertiliser types.

Evaluation of synthetic hydroxyapatite as a potential phosphorus fertilizer for application in Forest plantations

Synthetic hydroxyapatite (HA) was compared against triple superphosphate (TSP) and two unprocessed phosphate rocks (PR1, PR2) to (1) quantify and assess a synthetic lamellar structured-HA for its solubility and diffusiveness under acidic, sandy, soil conditions, (2) Evaluate synthetic lamellar structured-HA as a phosphorus early rotation fertilizer for Eucalyptus saplings. Soil incubation experiments verified that HA released more diffusive phosphorus into the soil than non-synthetic phosphate rock and had similar amounts of diffusive phosphorus as TSP. The solubility of HA at pH 3 and pH 6 was higher than that of raw ground phosphate rocks (apatites). Total dry-matter yield (DMY) and shoot-length of Eucalyptus seedlings grown for 154 days in acid soil (pH 4.9) were increased significantly by the application of HA compared to the control, PR2, and mixed (HA + PR2). The lack of a DMY response using TSP indicates that phosphorus may not have been the limiting factor. However, considering TSP and HA had similar solubilities and released diffusive phosphorus at similar levels, the only variable we failed to control for was the CaCO3 provided by the HA and not the TSP. Further experimentation is needed to confirm this hypothesis. Overall, HA is a promising candidate to supplement traditional phosphorus fertilizers for acidic sandy Eucalyptus silviculture.

Soil sampling depth and phosphorus extraction method for phosphorus in leguminous pastures

The current guidelines and recommendations for P fertilization in Uruguay can be improved by adjusting the sampling depth and analytical methods of testing soil P in pastures with different fertilization history. A set of field trials was conducted between 2008 and 2012 on 14 sites of Uruguay for the purpose of comparing two sampling depths and three methods for assessing P availability by their correlation with annual dry matter yield response. The trials had a randomized complete block design and were sown with Trifolium repens or Lotus corniculatus. Soil P availability was determined by sampling 0-7.5 and 0-15 cm depth using three analytical methods: Bray I, cationic resins, and citric acid. Rock phosphate and triple superphosphate were applied at five P rates. (0-240 kg kg P2O5 ha-1). Annual forage yield was recorded. Relative yield was calculated as measured yield/maximum yield observed within a block. The correlation between relative yield and soil P availability was studied using the modified arcsine-logarithm calibration curve (ALCC) and analyzing the resulting correlation coefficient, root-mean-square error (RMSE) of the soil P test, and RMSE of the relative yield. The 0-7.5 cm soil sampling depth did not show a better fit than the deeper sampling (0-15 cm), with the latter having less variation in soil P test values. When rock phosphate was used, the correlation coefficients were 0.50 for cationic resins, 0.53 for citric acid, and 0.38 for Bray I. When triple superphosphate was used, the correlation coefficients were 0.37 for cationic resins, 0.44 for citric acid and 0.43 for Bray I. For both P sources, the citric acid method with the sampling of 0-15 cm soil depth is the preferred soil P test method for management of P in leguminous pastures for the soils studied.

Response of Dry Matter Yield and Nutritive Value of Corn for Silage to Irrigation Water and Nitrogen

Response of Dry Matter Yield and Nutritive Value of Corn for Silage to Irrigation Water and Nitrogen

Response of Dry Matter Yield and Nutritive Value of Corn for Silage to Irrigation Water and Nitrogen

Response of Dry Matter Yield and Nutritive Value of Corn for Silage to Irrigation Water and Nitrogen

Tall fescue management and environmental influences on soil, surface residue, and forage properties

AbstractEnvironmental characteristics within a region often form site‐specific agro‐ecological responses to management. Using 92 fall‐stockpiled tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] field trials in North Carolina and surrounding states, our objective was to test the influence of two management factors (forage utilization and pasture age) and two environmental factors (elevation and soil textural gradients) on soil properties at 0‐to‐10‐cm depth, surface residue carbon (C) and nitrogen (N) contents, and absolute forage mass and nutritive values and their responses to N fertilization. Soil organic C and N fractions (i.e., total, particulate, and mineralizable) were greater (a) with improved (rotational stocking) than conventional (haying and/or continuous grazing) forage utilization, (b) in older pastures, (c) at higher elevation, and (d) with finer texture. Soil chemical properties were variably affected by these factors, and soil‐test P was not affected. Surface residue N tended to be greater with improved than conventional forage utilization, but surface residue C was not affected by any of the factors. Crude protein was greater and dry matter yield response to N fertilizer was lower with improved than with conventional forage utilization. Forage mass was lower and nutritive values were greater at higher elevation. Soil organic C and total soil N sequestration rates during a 25‐yr period were 0.75 Mg C ha−1 yr−1 and 75 kg N ha−1 yr−1, respectively. Elevation and soil texture imparted strong environmental controls on a diversity of soil properties, but management factors mostly affected surface‐soil organic C and N fractions, which helped sustain forage productivity and nutritive value with lower N fertilizer input.

Hop dry matter yield and cone quality responses to amino acid and potassium-rich foliar spray applications

The use of amino acid and K-rich foliar sprays was evaluated in a commercial hop field in North-eastern Portugal. Four applications of an amino acid-rich foliar spray were performed in place of a second side dress N application of ⁓70 kg N ha−1, which is usually applied by the farmer. The K-rich foliar spray was applied once at the cone developing stage as a supplement to the farmer’s fertilization plan. The amino acid-enriched foliar spray maintained crop dry matter yield at the levels of the control treatment and increased cone alpha-acids concentration (41.8% in 2018 and 9.3% in 2019). Foliar K did not increase cone dry matter yield, cone size or bitter acid concentration. Tissue K concentration was not significantly affected by foliar treatments whereas the application of K seemed to increase N uptake, with leaves and stems being the predominant allocation tissues. Both foliar treatments increased leaf and stem Mg concentrations. The results seem to emphasize the importance of amino acids in the biosynthesis of bitter acids, while K and Zn seemed to play an important secondary role, maybe related to N metabolism and its reduction into amino acids. The concentrations of total phenols in cones and leaves were lower in the foliar treatments in comparison to the control, and the higher values registered in leaves. In this study, the use of amino acids as a foliar spray provided an interesting result, since they maintained cone dry matter yield and increased cone bitter acid concentration with reduced N use.

Determination of Increase in Yield of Tropical Grasses Inoculated with Spirillum lipoferum

Increase in yield of tropical grasses viz. digit grass (Digitaria decumbens), guinea grass (Panicum maximum) and pearl millet (Penisetum americanum) inoculated with tropical nitrogen-fixing bacterium, Spirillum lipoferum was investigated. The study was carried out for three consecutive years (2016-2018). Dry matter yields and protein content of the three tropical grasses were used for the assessment. In 2017, pearl millet (Penisetum americanum) and guinea grass (Panicum maximum) produced significantly higher protein content and dry matter yields. Projected yields using regression analysis of both pearl millet and guinea grass indicated that about 40kgN ha-1 yr-1 were replaced by inoculation. Although, protein production of guinea grass was lower during 2018, dry matter yield responses were similar to those of 2017. This research has shown that inoculation with Spirillum lipoferum, a tropical nitrogen-fixing bacterium reduced acetylene and increased yields or reduced nitrogen fertilizer requirement of the tropical grasses as well as replacement of up to 40KgN ha-1. This amount is agro-economically important and suggests the viability and potential for grass-bacteria systems.

Productivity and Topsoil Quality of Young and Old Permanent Grassland: An On-Farm Comparison

Renewing agricultural grasslands for improved yields and forage quality generally involves eliminating standing vegetation with herbicides, ploughing and reseeding. However, grassland renewal may negatively affect soil quality and related ecosystem services. On clay soil in the north of the Netherlands, we measured grass productivity and soil chemical parameters of ‘young’ (5–15 years since last grassland renewal) and ‘old’ (>20 years since last grassland renewal) permanent grasslands, located as pairs at 10 different dairy farms. We found no significant difference with old permanent grassland in herbage dry matter yield and fertilizer nitrogen (N) response, whereas herbage N yield was lower in young permanent grassland. Moreover, the young grassland soil contained less soil organic matter (SOM), soil organic carbon (C) and soil organic N compared to the old grassland soil. Grass productivity was positively correlated with SOM and related parameters such as soil organic C, soil organic N and potentially mineralizable N. We conclude that on clay soils with 70% desirable grasses (i.e., Lolium perenne and Phleum pratense) or more, the presumed yield benefit of grassland renewal is offset by a loss of soil quality (SOM and N-total). The current practice of renewing grassland after 10 years without considering the botanical composition, is counter-productive and not sustainable.

Cutting management of alfalfa‐based mixtures in contrasting agroclimatic regions

AbstractCutting schedules affect forage yield, nutritive value, and persistence but few studies have recently assessed the effect of intensive cutting schedules on alfalfa (Medicago sativa L.)‐based mixtures. We determined the effects of (a) cutting at early bud vs. early bloom of alfalfa, (b) a fall cut, (c) alfalfa–grass mixture vs. pure alfalfa, (d) one vs. two grasses, and (e) tall fescue (Schedonorus arundinacea [Schreb.] Dumort.) vs. timothy (Phleum pratense L.) in an experiment over four post‐seeding years at four sites with four cutting schedules on four alfalfa‐based mixtures. Cutting alfalfa at early bud rather than early bloom reduced annual forage dry matter (DM) yield by 2.03 Mg ha−1 and alfalfa contribution to DM yield by 17 percentage units, increased forage total digestible nutrient (TDN) concentration by 44 g kg−1 DM but did not increase estimated annual milk production per hectare. A fall cut did not improve annual forage DM yield and estimated annual milk production per hectare but reduced alfalfa contribution to DM yield. Pure alfalfa resulted in 1.09 Mg DM ha−1 less annual forage DM yield than alfalfa grown with one or two grasses. Two forage grasses with alfalfa compared with just one grass had no effect on forage DM yield and estimated annual milk production per hectare. The response of forage DM yield and estimated annual milk production per hectare to timothy or tall fescue with alfalfa varied with site but forage TDN concentration and alfalfa contribution to DM yield were generally greater with timothy than tall fescue.

Effects of nitrogen application rate on productivity, nutritive value and winter tolerance of timothy and meadow fescue cultivars

AbstractFinnish N fertilizer application regulations for forage grasses are based on field experiments mainly conducted in the 1960–1970s with cultivars and management practices typical of the time. In order to update the yield response function of N, to make it better suited to current grassland farming, field experiments were conducted at two sites in 2015–2017 with two cultivars of timothy (Phleum pratense L.) and one of meadow fescue (Festuca pratensis Huds.). Dry matter (DM) yield, nutritive value and N balance were evaluated, with N application levels 0, 150, 200, 250, 300, 350, 400 and 450 kg N ha−1 year−1. The grasses were harvested three times per season. The data indicate that the DM yield response was significantly stronger, and N was used more efficiently for DM production than earlier without compromising the nutritive value, especially during the first two years. The third harvest produced on average 23% of the annual yield, utilizing N efficiently. N application rates below 350 kg N ha−1 year−1 did not cause substantial overwintering losses or lodging. The data indicate that with changing climate and improved cultivars and management practices, there is a need to modify the rates and timing of N application. The results suggest that N application levels could be increased by at least 50 kg N ha−1 year−1 from the current maximum accepted rate (250 kg N ha−1 year−1) without too high NO3‐ or CP concentrations in feed, or too high N balance that indicates increasing risk of N leaching.

Grain yield responses to planting density in twin and narrow row cultivation of early cultivars in maize

AbstractWe investigated how the responses of grain yield of maize to planting density depended on planting pattern (twin row, TR; narrow row, NR; narrow twin row, NTR; compared with conventional row (CR) cultivation) over 2 years using cultivars with relative maturity of 93 days. Grain yields were higher in order of NTR ≥ TR ≥ NR ≥ CR in all planting densities. Changes in grain yield and total dry matter yield with planting density followed significant negative quadratic regression curves in all planting patterns, increased with dense planting from 9.7 to 10.4 planting density and decreased thereafter. Changes in number of grains per ear and hundred grain weight with planting density followed significant negative linear regression in all planting pattern, and number of grain per ear, hundred grain weight and harvest index decreased with dense planting. The quadratic coefficient of the quadratic regression model, which indicates the changeability of the planting density response of grain yield, was lowest for NTR, followed by TR, NR and CR. The decline in number of grains per ear in response to increasing planting density for different planting patterns was NTR ≤ TR ≤ NR ≤ CR. The planting density response of total dry matter yield closely follows that of the grain yield in all planting pattern. But decrease in harvest index due to increased planting density for different planting patterns was lowest for NTR, followed by TR, NR and CR. Considering the relationship of grain yield to their related traits, the improved stability of grain yield for the specific planting patterns from the fact that the decline in number of grains per ear for different planting patterns is NTR < TR ≤ NR < CR. The specific planting patterns moderate the decline in harvest index and number of grains per ear with increasing planting density by enabling the maintenance of greater inter‐individual distance a given planting density.

Dry Matter Yield Response to Seeding Rate and Row Spacing in Direct-seeded and Double-harvested Forage Rice

Dry Matter Yield Response to Seeding Rate and Row Spacing in Direct-seeded and Double-harvested Forage Rice

Effect of Increasing Species Diversity and Grazing Management on Pasture Productivity, Animal Performance, and Soil Carbon Sequestration of Re-Established Pasture in Canadian Prairie.

Simple SummaryCanadian grasslands are recognized for providing high quality forage for grazing livestock and wildlife. The study was conducted on a re-established pasture in a Western Canadian semi-arid climate to investigate the effect of pasture species mixture and grazing management on pasture productivity, animal performance, and soil carbon sequestration. Pasture productivity and animal response were independent of pasture mixture but affected by grazing management. Average pasture dry matter productivity was greater with deferred-rotational grazing while pasture quality and animal gain were higher with continuous grazing. Soil carbon change varied with pasture seed mixture and grazing management interaction where pasture with 7-species mixture under continuous grazing had the lowest soil carbon gain. The objective of the study was to determine the effect of type of pasture mix and grazing management on pasture productivity, animal response and soil organic carbon (SOC) level. Pasture was established in 2001 on 16 paddocks of 2.1 ha that had been primarily in wheat and summer fallow. Treatments consisted of a completely randomized experimental design with two replicates: two pasture mixes (7-species (7-mix) and 12-species (12-mix)) and two grazing systems (continuous grazing (CG) and deferred-rotational grazing (DRG)). Pasture was stocked with commercial yearling Angus steers (Bos Taurus, 354 ± 13 kg) between 2005 and 2014. All pastures were grazed to an average utilization rate of 50% (40% to 60%). Average peak and pre-grazing pasture dry matter (DM) yield and animal response were independent of pasture seed mixture but varied with grazing management and production year. Average peak DM yield was 26.4% higher (p = 0.0003) for pasture under DRG relative to CG (1301 kg ha−1). However, total digestible nutrient for pasture under DRG was 4% lower (p < 0.0001) as compared to CG (60.2%). Average daily weight gain was 18% higher (p = 0.017) for CG than DRG (0.81 kg d−1), likely related to higher pasture quality under CG. Soil carbon sequestration was affected by seed mixture × grazing system interaction (p ≤ 0.004). Over the fourteen years of production, pasture with 7-mix under CG had the lowest (p < 0.01) average SOC stock at 15 cm (24.5 Mg ha−1) and 30 cm depth (42.3 Mg ha−1). Overall, the results from our study implied that increasing species diversity for pasture managed under CG may increase SOC gain while improving animal productivity.

The development and application of functions describing pasture yield responses to phosphorus, potassium and sulfur in Australia using meta-data analysis and derived soil-test calibration relationships

An improved ability to predict pasture dry matter (DM) yield response to applied phosphorus (P), potassium (K) and sulfur (S) is a crucial step in determining the production and economic benefits of fertiliser inputs and the environmental benefits associated with efficient nutrient use. The adoption and application of soil testing can make substantial improvements to nutrient use efficiency, but soil test interpretation needs to be based on the best available and most relevant experimental data. This paper reports on the development of improved national and regionally specific soil test–pasture yield response functions and critical soil test P, K and S values for near-maximum growth of improved pastures across Australia. A comprehensive dataset of pasture yield responses to fertiliser applications was collated from field experiments conducted in all improved pasture regions of Australia. The Better Fertiliser Decisions for Pastures (BFDP) database contains data from 3032 experiment sites, 21918 yield response measures and 5548 experiment site years. These data were converted to standard measurement units and compiled within a specifically designed relational database, where the data could be explored and interpreted. Key data included soil and site descriptions, pasture type, fertiliser type and rate, nutrient application rate, DM yield measures and soil test results (i.e. Olsen P, Colwell P, P buffering, Colwell K, Skene K, exchangeable K, CPC S, KCl S). These data were analysed, and quantitative non-linear mixed effects models based upon the Mitscherlich function were developed. Where appropriate, disparate datasets were integrated to derive the most appropriate response relationships for different soil texture and P buffering index classes, as well as interpretation at the regional, state, and national scale. Overall, the fitted models provided a good fit to the large body of data, using readily interpretable coefficients, but were at times limited by patchiness of meta-data and uneven representation of different soil types and regions. The models provided improved predictions of relative pasture yield response to soil nutrient status and can be scaled to absolute yield using a specified maximal yield by the user. Importantly, the response function exhibits diminishing returns, enabling marginal economic analysis and determination of optimum fertiliser application rate to a specific situation. These derived relationships form the basis of national standards for soil test interpretation and fertiliser recommendations for Australian pastures and grazing industries, and are incorporated within the major Australian fertiliser company decision support systems. However, the utility of the national database is limited without a contemporary web-based interface, like that developed for the Better Fertiliser Decisions for Cropping (BFDC) national database. An integrated approach between the BFDP and the BFDC would facilitate the interrogation of the database by advisors and farmers to generate yield response curves relevant to the region and/or pasture system of interest and provides the capacity to accommodate new data in the future.