Herbage and nitrogen yields,fixation and transfer by white clover to companion grasses in grazed swards under different rates of nitrogen fertilization

In grass–legume swards, biologically fixed nitrogen (N) from the legume can support the N requirements of the grass, but legume N fixation is suppressed by additional fertilizer N application. This study sought to identify a fertilizer N application rate that maximizes herbage and N yields, N fixation and apparent N transfer from white clover to companion grasses under intensive grazing at a site with high soil‐N status. During a 3‐year period (2011–2013), swards of perennial ryegrass and of perennial ryegrass–white clover, receiving up to 240 kg N ha^?1 year^?1, were compared using isotope dilution and N‐difference methods. The presence of white clover increased herbage and N yields by 12–44% and 26–72%, respectively. Applications of N fertilizer reduced sward white clover content, but the effect was less at below 120 kg N ha^?1. The proportion of N derived from the atmospheric N fixation was 25–70%. Nitrogen fixation ranged from 25 to 142 kg N ha^?1 measured using the isotope dilution method in 2012 and from 52 to 291 kg N ha^?1 using the N‐difference method across all years. Fertilizer N application reduced the percentage and yield of fixed N. Transfer of N from white clover to grass was not confirmed, but there was an increased N content in grass and soil‐N levels. Under intensive grazing, the maximum applied N rate that optimized herbage and N yields with minimal effect on white clover content and fixation rates was 60–120 kg N ha^?1.     

Use of a systems synthesis approach to model nitrogen losses from dairy farms in south-west England

Nitrogen (N) budgets were determined for six typical, moderately intensive dairy farms in south‐west England. Proportionately, only 0·12–0·17 of the N input to the farms was recovered in agricultural products, leaving annual N surpluses equivalent to 249–376 kg N ha^?1. A sequence of models (MANNER, NCYCLE and SUNDIAL) was used, together with the estimated N balance of the dairy cows and standard ammonia emission factors, to estimate N losses for each farm. Total estimated losses were equivalent to 137–220 kg N ha^?1 year^?1. Leaching accounted for 0·26–0·45 of the total loss, ammonia volatilization for 0·27–0·39 and denitrification for 0·17–0·36. When residual N from manure applications was included, there appeared to be an annual accumulation of soil N, equivalent to 66–158 kg N ha^?1 when averaged over the whole farm area. The amounts of N lost by leaching, volatilization and denitrification, and accumulated as soil‐N, were determined by a combination of farm properties, including N input, soil type, drainage, characteristics of the manure produced and type of fertilizer. The sum of estimated losses and change in N retained on the farm was between 0·85 and 1·11 of the N surplus (input minus output) determined from the farm budget. This suggests that losses and the change in soil‐N were underestimated on some farms and overestimated on others (by up to ?50 and +23 kg N ha^?1 respectively). Much of the discrepancy between estimates and the surplus was attributed to difficulties of fully integrating inputs and outputs between the different models and stages of the modelling procedure.     

Successive annual applications of organic manures for cut grass: short-term observations on utilization of manure nitrogen

Abstract The recovery of nitrogen (N) from, and the fertilizer‐N value of, low dry‐matter (DM) cattle slurry and farm yard manure (FYM), applied annually to perennial ryegrass swards grown at two sites, on sandy loam and shallow calcareous silty clay loam soils, were studied over a 4‐year period. Slurry or FYM, applied at target rates of either 150 kg N ha^?1 or 300 kg N ha^?1 in either October, February or May/June, in combination with 150 kg N ha^?1 inorganic fertilizer‐N (applied as split dressings before the first and second grass cut), were compared with a set of inorganic fertilizer‐N response treatments. DM yield, N offtake, apparent manure‐N recovery (in herbage) and manure‐N efficiency (compared with inorganic fertilizer‐N) were determined at two silage cuts each summer. Soil mineral nitrogen (SMN) measurements in autumn and spring were used to assess potential N leaching loss over winter and to quantify available N residues in the soil in spring. Apparent manure‐N recovery and manure‐N efficiency were usually greater from slurry applications in February than from those in October, but the timing of the application of FYM had a much smaller effect, compared with the timings of the application of slurry, on the utilization of N from manure by grass. Spring assessment of SMN was useful in quantifying available N residues from October slurry applications. Manure‐N recovery for all application timings was, on average, higher from the sandy loam than the shallow calcareous clay loam. The application of slurry to grass in early spring, at a rate of 150 kg total N ha^?1, with the addition of a supplementary 50 kg inorganic fertilizer‐N ha^?1, was the most suitable strategy for utilizing slurry‐N effectively and for supplying the N requirement for first‐cut silage.     

Biomass yield and nutrient content of a tropical mulberry forage bank: effects of season,harvest frequency and fertilization rate

Effects of season (SEAS), organic fertilization with laying hen manure (N) and harvest frequency (FREQ) on forage yield and composition were evaluated in a high‐density mulberry forage bank, established under low‐input tropical farming conditions. The experiment, replicated over two consecutive years, was arranged in 18 treatments resulting from a 3 × 3×2 factorial design which combined three FREQ (60, 90 and 120 d), 3 N rates (100, 300 and 500 kg N ha^?1 year^?1) and the two seasons (RAIN and DRY). Forage yield, leaf‐to‐stem ratio, the edible fraction (EDIB, %), nutrient content and the maturity indexes were monitored. Either forage yield or qualities by plant fraction were strongly affected by SEAS, FREQ, N rate and by their interactions. Effects of FREQ and N were modulated by SEAS. Increasing FREQ during RAIN negatively affected EDIB yield and quality after 90 d, while increasing ligneous fraction. During DRY, longer FREQ allowed higher total forage and EDIB yields. Leaves were more abundant in RAIN, and its yield was increased with fertilization but only during this season. Maturity indexes were higher in DRY than in RAIN. Under the conditions of this experiment, harvesting at 60 and 90 d in RAIN and DRY, respectively, with an N rate of 300 kg N ha^?1 year^?1 seems the best agronomic choice for an optimal compromise between forage yield and nutritive value.     

Urea and composted cattle manure affect forage yield and nutritive value in sandy soils of south‐central Vietnam

Improved forage management can support increased production in smallholder beef systems. Our objective was to evaluate the effects of mineral nitrogen (urea) and composted cattle manure on Brachiaria cv. Mulato II yield and nutritive value in south‐central coastal Vietnam. Study design was a randomized complete block on six farms (blocks), with treatments derived from the factorial combination of five rates of composted cattle manure (0, 4, 8, 12 and 24 Mg DM ha^?1 year^?1) and three urea rates (0, 60 and 120 kg N ha^?1 year^?1), split into six yearly applications. Yield was measured from 2011 to 2013 with 36‐day average harvest intervals. Forage nutritive value was measured in September 2011 and December 2012. Highest yields were achieved when both compost and urea were applied at high rates. The initial yield and tiller responses to urea application were not sustained over the duration of the study when no compost was applied. Compost applied in isolation did not increase yield. Compost application increased ash concentration. Urea increased nutrient yield for all forage nutritive value parameters measured. Composted cattle manure combined with urea benefits grass yield, but high application rates are needed for sustained high yields on sandy soils.     

Performance and environmental effects of forage production on sandy soils. II. Impact of defoliation system and nitrogen input on nitrate leaching losses

A field experiment was conducted over a 4‐year period to determine NO₃ leaching losses from grassland on a freely draining sandy soil. The experiment consisted of all combinations of five defoliation systems; cutting‐only (CO), rotational grazing (GO), mixed systems with one (MSI) or two silage cuts (MSII) plus subsequent rotational grazing, and simulated grazing (SG), four mineral nitrogen (N) application rates (0, 100, 200, and 300 kg N ha^?1 year^?1), and two slurry levels (0 and 20 m³ slurry ha^?1 year^?1). Due to the high N return by grazing animals, leaching losses in the rotational grazing systems generally were associated with NO₃‐N concentrations which exceeded the EU limit for drinking water. NO₃ leaching losses in a rotational grazing system could be reduced by lowering the N fertilizer intensity and the inclusion of one or two silage cuts in spring. However, even in the unfertilized mixed systems, N fixation by white clover exceeded the amounts of N removed via animal products, which resulted in NO₃‐N concentrations well above the EU limit for drinking water. In terms of leaching losses, the cutting‐only system was the most advantageous treatment. NO₃ leaching losses on grassland could be predicted by the amount of soil mineral N at the end of the growing season and by the N surplus calculated from N balances at the field scale. From the results obtained a revised nitrogen fertilization policy and a reduced grazing intensity by integrating silage cuts are suggested.     

The effect of the nitrification inhibitor dicyandiamide (DCD) on spring and annual herbage production in urine patches when applied in late summer or early autumn

A cut plot experiment was undertaken at two sites in Ireland, one a free‐draining acid brown earth at Moorepark (MPK) and the other a fine loam soil with imperfect drainage at Johnstown Castle (JC). The effect of applying the nitrification inhibitor dicyandiamide (DCD) at 10 kg ha^?1 in July, August and September or not applying DCD to plots receiving synthetic urine or zero urine on spring and annual herbage production was examined. In the experiment, each site received 350 kg nitrogen (N) fertilizer ha^?1 year^?1. The application of DCD in August at a rate of 10 kg ha^?1 significantly increased spring and annual herbage production by 14 and 15%, respectively, at MPK, when applied following urine application in year 1. There was no effect of DCD applied in year 1 on herbage production at JC. The application of DCD in August resulted in lower soil total oxidized N (TON) content up to sampling day 56 post‐urine application, at MPK in year 1, retaining higher N content in the soil. There was no effect of DCD on any of the parameters measured in year 2 at MPK or at JC. Urine application did not increase spring herbage production at either site. Urine application significantly increased annual herbage production at MPK only in year 1. Urine application increased annual herbage N uptake, herbage crude protein (CP) content and soil mineral N at both sites in both years.     

Bahiagrass response and N loss from selected N fertilizer sources

The increasing cost of commercial fertilizers and environmental problems associated with improper fertilization management have prompted the need to re‐examine commercial N sources that can effectively supply N to pastures while minimizing N losses. This 3‐year study evaluated the effects of selected N sources on bahiagrass (Paspalum notatum Flügge) responses, soil properties and N losses. Treatments consisted of a factorial combination of 6 N sources [(i) ammonium nitrate (AN), (ii) ammonium sulphate (AS), (iii) urea (U), (iv) urea treated with Agrotain (U + Agrotain), (v) SuperU and (vi) ammonium sulphate nitrate] and 3 N levels (0, 60 or 120 kg ha^?1 year^?1), replicated three times. Bahiagrass dry‐matter yield (DMY), crude protein (CP) concentration, N uptake and recovery were not affected by N source, with the exception of AN that resulted in reduced DMY in 2010 compared with the other sources. Bahiagrass DMY, CP concentration, N uptake and recovery increased linearly as N levels increased. Nitrogen fertilization showed no effect on soil pH or soil N accumulation. Soil pore‐water N concentrations from treatments fertilized with N were similar to the control plots indicating no threat to the environment. At the N levels evaluated in this study, selection of N source should be based on the fertilizer cost.     

Performance and environmental effects of forage production on sandy soils. I. Impact of defoliation system and nitrogen input on performance and N balance of grassland

Grassland and its management is central to the productivity of and nitrogen (N) losses from dairy farms in north‐west Europe. Botanical composition, production and N surplus of grassland were assessed during five consecutive years. The experiment consisted of all combinations of five defoliation systems: cutting‐only (CO), rotational grazing (GO), grazing + one (MSI) or two silage cuts (MSII) and simulated grazing (SG). Four mineral N fertilization rates (0–300 kg N ha^?1 year^?1) and two slurry levels (0 and 20 m³ slurry ha^?1 year^?1) were applied. Fertilizer N was more efficient in producing net energy (NEL) in grazing‐dominated, low white clover systems (GO and MSI systems: 70 and 88 MJ NEL kg^?1 N) than in white clover‐rich systems (MSII, CO and SG systems: ≤60 MJ NEL kg^?1 N). While sward productivity in system MSI was similar to that in system GO, system MSII benefited from increased N₂ fixation at low N rates. There were small differences in NEL concentrations of the herbage between defoliation systems. Crude protein concentration of the herbage increased with increasing N supply from fertilizer, excreta and N₂ fixation. N surpluses (?63 to +369 kg N ha^?1 year^?1) increased with increasing grazing intensity and increasing N fertilization rate. The average response in N surplus applied was 0·81, 0·59, 0·40, 0·33 and 0·24 kg N ha^?1 in systems GO, MSI, MSII, CO and SG respectively.     

The effect of stocking rate and calving date on grass production,utilization and nutritive value of the sward during the grazing season

A 2‐year whole‐farm system study compared the accumulation, utilization and nutritive value of grass in spring‐calving grass‐based systems differing in stocking rate (SR) and calving date (CD). Six treatments (systems) were compared over two complete grazing seasons. Stocking rates used in the study were low (2·5 cows ha^?1), medium (2·9 cows ha^?1) and high (3·3 cows ha^?1), respectively, and mean CDs were 12 February (early) and 25 February (late). Each system had its own farmlet of eighteen paddocks and one herd that remained on the same farmlet area for the duration of the study. Stocking rate had a small effect on total herbage accumulation (11 860 kg DM ha^?1 year^?1), but had no effect on total herbage utilization (11 700 kg DM ha^?1 year^?1). Milk and milk solids (MS; fat + protein) production per ha increased by 2580 and 196 kg ha^?1 as SR increased from 2·5 to 3·3 cows ha^?1. Milk production per ha and net herbage accumulation and utilization were unaffected by CD. Winter feed production was reduced as SR increased. Increased SR, associated with increased grazing severity, resulted in swards of increased leaf content and nutritive value. The results indicate that, although associated with increased milk production per ha, grazed grass utilization and improved sward nutritive value, the potential benefits of increased SR on Irish dairy farms can only be realized if the average level of herbage production and utilization is increased.     

Effects of cutting or grazing grass swards on herbage yield, nitrogen uptake and residual soil nitrate at different levels of N fertilization

On a Flemish sandy loam soil, cut and grazed swards were compared at different levels of mineral nitrogen (N) fertilization. Economically optimal N fertilization rates were 400 (or more) and 200 kg N ha^?1 yr^?1 on cut and grazed swards respectively. Considering the amounts of residual soil nitrate‐N in autumn, these N rates also met the current Flemish legal provisions, i.e. no more than 90 kg ha^?1 nitrate‐N present in the 0–90 cm soil layer, measured between 1 October and 15 November. The N use efficiency was considerably higher in cut grassland systems than in grazed systems, even when the animal component of a cut and conservation system was included. The results indicate that, for cut grasslands, two N application rates should be considered: intensively managed grasslands with high amounts of N (400 kg ha^?1 yr^?1 or more) or extensively managed grasslands with white clover and no more than 100 kg N ha^?1 yr^?1.     

Biomass production and nutrient removal by tropical grasses subsurface drip‐irrigated with dairy effluent

Effluent lagoons on dairy farms can overflow and potentially pollute adjacent land and associated water bodies. An alternative solution to effluent disposal is needed by dairy operators in island environments. An attractive win‐win alternative is to recycle nutrients from this resource through effluent irrigation for forage grass production that minimizes environmental pollution. This study assessed biomass production and nutrient removal by, and high application rates to, tropical grasses that were subsurface drip‐irrigated with dairy effluent. Four grass species – Banagrass (Pennisetum purpureum K. Schumach.), California grass (Brachiaria mutica (Forssk.) Stapf.), Stargrass (Cynodon nlemfuensis Vanderyst) and Suerte grass (Paspalum atratum Swallen) – were subsurface (20–25 cm) drip‐irrigated with effluent at two rates based on potential evapotranspiration (ET_p) at the site (Waianae, Hawaii) ?2·0 ET_p (16 mm d^?1 in winter; 23 mm d^?1 in summer) and 0·5 ET_p (5 mm d^?1 in winter; 6 mm d^?1 in summer). Treatments were arranged in an augmented completely randomized design. Brachiaria mutica and P. purpureum had the highest dry‐matter yield (43–57 t ha^?1 year^?1) and nutrient uptake especially with the 2·0 ET_p irrigation rate (1083–1405 kg ha^?1 year^?1 N, 154–164 kg ha^?1 year^?1 P, 1992–2141 kg ha^?1 year^?1 K). Average removal of nutrients by the grasses was 25–94% of the applied nitrogen, 11–82% of phosphorus and 2–13% of the potassium. Average values of crude protein (90–160 g kg^?1), neutral detergent fibre (570–620 g kg^?1) and acid detergent fibre (320–360 g kg^?1) were at levels acceptable for feeding to lactating cattle. Results suggest that P. purpureum and B. mutica irrigated with effluent effectively recycled nutrients in the milk production system.     

Yield response of long-term mixed grassland swards and nutrient cycling under different nutrient sources and management regimes

Abstract The response of a long‐term, mixed‐species hayfield in Maine, USA, to commercial fertilizers and liquid dairy manure was evaluated over a 6‐year period, including the effects on yield, nutrient concentration and cycling, forage species composition and soil nutrient levels. Nutrient treatments included an unamended control, N fertilizer, NPK fertilizer and liquid dairy manure (LDM). The application rates of plant‐available N, P, and K were constant across treatments. Application of nutrients in any form increased forage yield, generally by 2–4 t dry matter (DM) ha^?1 year^?1. Yield from NPK fertilizer was 0·05–0·25 higher than from LDM, due to differences in N availability. Yield responses to P and K were minimal and there appeared to be no difference between P and K in fertilizer and manure. The forage sward became increasingly dominated by grass species as the experiment progressed; application of P and K in fertilizer or LDM allowed Agropyron repens to increase at the expense of Poa pratensis. Forage nutrient removal accounted for all applied N and K, and nearly all applied P, throughout the study period, demonstrating the important role these forages can play in whole‐farm nutrient management.     

Red clover for silage: management impacts on herbage yield,nutritive value,ensilability and persistence,and relativity to perennial ryegrass

This 6‐year experiment quantified the impacts of management factors on red clover yield, persistence, nutritive value and ensilability, and compared these with perennial ryegrass receiving inorganic N fertilizer. Within a randomized complete block design, field plots were used to evaluate a 2 (cultivar, Merviot and Ruttinova) × 2 (alone and with perennial ryegrass) × 2 (0 and 50 kg fertilizer N ha^?1 in mid‐March) × 2 (harvest schedule) combination of the factors relating to red clover, and a 2 (harvest schedule) × 4 (0, 50, 100 and 150 kg N ha^?1 for each cut) combination of the factors relating to perennial ryegrass. The early and late harvest schedules both involved four cuts per year, but commenced a fortnight apart. Red clover treatments averaged 14 906 kg dry matter (DM) ha^?1 per year, whereas perennial ryegrass receiving 600 kg inorganic N fertilizer per year averaged 14 803 kg DM ha^?1 per year. There was no yield decline evident across years despite a decline in the proportion of red clover. The early harvest schedule and sowing ryegrass with red clover increased the herbage yield and digestibility. March application of fertilizer N to red clover treatments reduced the annual yield. Early harvest schedule increased and both fertilizer N and sowing with ryegrass decreased the proportion of red clover. Sowing with ryegrass improved the indices of ensilability, but reduced the crude protein content. Both red clover cultivars had similar performance characteristics. A selected red clover‐based treatment, considered to exhibit superior overall production characteristics, outyielded N‐fertilized perennial ryegrass in mid‐season. However, it had poorer digestibility and ensilability indices.     

Radiation‐use efficiency for forage kale crops grown under different nitrogen application rates

Crop growth is related to radiation‐use efficiency (RUE), which is influenced by the nitrogen (N) status of the crop, expressed at canopy level as specific leaf N (SLN) or at plant level as N nutrition index (NNI). To determine the mechanisms through which N affects dry‐matter (DM) production of forage kale, results from two experiments (N treatment range 0–500 kg ha^?1) were analysed for fractional radiation interception (RI), accumulated radiation (R_acc), RUE, N uptake, critical N concentration (N_c), NNI and SLN. The measured variables (DM, RI and SLN) and the calculated variables (NNI, R_acc and RUE) increased with N supply. RUE increased from 0·74 and 0·89 g MJ^?1 IPAR for the control treatments to 1·50 and 1·95 g MJ^?1 IPAR under adequate N and water in both experiments. This represented an increase in RUE of 52–146% for the range of N treatments used in both experiments, whilst R_acc increased by 9–17%, compared with the control treatments. Subsequently, the total DM yield of kale increased from 6·7 and 8 t DM ha^?1 for the control treatments to ≥ 19 t DM ha^?1 when ≥150 kg N ha^?1 was applied. The DM yields for the 500 kg N ha^?1 treatments were 25·5 and 27·6 t DM ha^?1 for the two experiments. RUE increased linearly with SLN, at an average rate of 0·38 g DM MJ^?1 IPAR per each additional 1 g N m^?2 leaf until a maximum RUE of 1·90 g MJ^?1 IPAR was reached in both experiments. There were no changes in RUE with SLN of > 2·6 g m^?2 and NNI >1, implying luxury N uptake. RUE was the most dominant driver of forage kale DM yield increases in response to SLN and NNI.     

Comparative effects of food processing liquid slurry and inorganic fertilizers on tanner grass (Brachiaria arrecta) pasture: grass yield,crude protein and P levels and residual soil N and P

This small‐plot field study evaluated food processing liquid slurry (FPLS) as a potential fertilizer for tanner grass (Brachiaria arrecta) production on an acidic loam soil. The treatments, arranged in a randomized complete block design with three replicates, consisted of an unfertilized control, inorganic fertilizer applied at 50 and 200 kg nitrogen (N) ha^?1 with and without phosphorus (P) at 50 kg P ha^?1, and FPLS applied at 50 and 200 kg N ha^?1. Compared to the unfertilized control, the FPLS applied at 200 kg N ha^?1 significantly increased grass dry‐matter yield (DMY), herbage crude protein (CP) and P content, and N and P uptake in the second of two trials and P uptake in both trials. However, DMY and contents, of CP and P were generally lower for the FPLS treatments compared to the inorganic fertilizers. Apparent N recovery was higher for the inorganic fertilizer treatments than FPLS treatments in trial 1, while apparent P recovery was similar among all treatments in both trials. The FPLS treatments did not significantly increase soil NO₃‐N and P concentrations, but increased NH₄‐N in the 0–15 cm layer. The results suggest that application of FPLS to tanner grass pastures is an alternative to its disposal in landfill.     

Plant and soil responses to nitrogen and phosphorus fertilization of bromegrass‐dominated haylands in Saskatchewan,Canada

Field experiments were conducted at three different sites in Saskatchewan, Canada (Colonsay, Vanscoy and Rosthern) over two years (2005 and 2006) to determine the effects of dribble‐banded and coulter‐injected liquid fertilizer applied in the spring of 2005 at 56, 112 and 224 kg N ha^?1 with and without P at 28 kg P₂O₅ ha^?1. The three sites were unfertilized, 7‐ to 8‐year old stands of mainly meadow bromegrass (Bromus riparius)‐dominated haylands. All fertilization treatments produced significantly (P ≤ 0·05) higher dry matter yield than the control in the year of application at the three Saskatchewan sites. There was no significant difference between the two application methods (surface dribble band vs. coulter injected) for any fertilizer treatments. The addition of 28 kg P₂O₅ ha^?1 P fertilizer along with the N fertilizer did not have a significant effect on yield in most cases. In the year of application, increasing N rates above 56 kg N ha^?1 did not significantly increase yield over the 56 kg N ha^?1 rate in most cases, but did increase N concentration, N uptake and protein concentration. A significant residual effect was found in the high N‐rate treatments in 2006, with significantly higher yield and N uptake. In 2005, the forage N and P uptake in the fertilized treatments were significantly higher than the control in all cases. The N uptake at the three Saskatchewan sites increased with increasing N rate up to the high rate of 224 kg N ha^?1, although the percent recovery of applied N decreased with increasing rate. The P fertilization with 28 kg P₂O₅ ha^?1 also increased P uptake. Overall, rates of fertilizer of approximately 56 kg N ha^?1 appear to be sufficient to produce nearly maximum forage yield and protein concentration of the grass in the year of application.     

Effects of 5 years of digestate application on biomass production and quality of cocksfoot (Dactylis glomerata L.)

Anaerobic digestion of biomass produces biogas for combustion and also provides a residual digestate. Although sometimes regarded as a waste product, the nutrient‐rich chemical composition of digestate makes it a potential organic fertilizer for agriculture. The goal of this study was to evaluate the effectiveness of digestate as a fertilizer on the biomass yield and chemical composition of cocksfoot (Dactylis glomerata L.). In a 5‐year small‐plot field experiment digestate fertilization treatments supplying 90, 180, 270, 360 and 450 kg N ha^?1 were compared with untreated plots and plots fertilized with 180 kg N ha^?1 of mineral N fertilizer. Swards fertilized with digestate produced higher biomass yield compared with the control. The same rate of nitrogen fertilizer (180 kg N ha^?1) supplied as digestate and from mineral fertilizers gave similar results on biomass yield. Herbage in swards fertilized with digestate contained less nitrogen, but the C:N ratio was much more suitable for biogas production. Digestate fertilization resulted in higher concentrations of cellulose and hemicellulose in biomass and lower contents of the inhibitors of anaerobic digestion—sulphur, calcium, magnesium and phosphorus—compared with those of swards receiving mineral fertilizers.     

Production and nutritional value of sorghum and black oat forages under nitrogen fertilization

The effect of nitrogen (N) fertilization on the dry‐matter (DM) yield and nutritional value of sorghum (Sorghum sp., cv. Jumbo) and black oat (Avena strigosa cv., IPR 61) was investigated in the context of forage and livestock production in southern Brazil. Sorghum was cultivated with 0, 37·5, 75, 150, 225, 300 and 375 kg N ha^?1 during the summer crop seasons of 2010/11 and 2011/12. Black oat received 0, 40, 80, 120, 160, 200 and 240 kg N ha^?1 in the winter of 2011. According to the adjusted polynomial regression, sorghum DM yield increased in response to N up to 288 (12·9 t ha^?1) and 264 kg ha^?1 (5·6 t ha^?1) in 2010/11 and 2011/12 respectively. Crude protein (CP) content of sorghum was highest at 349 and 328 kg N ha^?1, but in vitro dry‐matter digestibility (IVDMD) was highest at 212–207 kg N ha^?1 in 2010/11 and 2011/12 respectively. Sorghum neutral detergent fibre (NDF) and acid detergent fibre (ADF) were not affected by N fertilization. In black oat, the maximum DM yield (6·0 t ha^?1) was obtained with 187 kg N ha^?1; the IVDMD, NDF and ADF were not affected by N fertilization, but the CP content increased up to 220 kg N ha^?1. It is concluded that these forage species can improve the year‐to‐year amount and quality of forage produced but high rates of N fertilizer are required to achieve high yields. Fertilizer N rates of 210–280 kg N ha^?1 in sorghum and 180 kg N ha^?1 in black oat in the crop rotation provide the greatest responses in DM yield consistent with good nutritional quality for livestock production.     

Orchardgrass response to different types,rates and application patterns of dairy manure

Manure management is a difficult task on many intensive dairy farms. Crops that can utilize large quantities of manure N, yield quality forage with larger rates of manure application, and allow manure spreading at different times in a year can simplify that task. A study was conducted in 1990 and 1991 on a Copake sandy loam soil (mixed mesic) in New Milford, Connecticut. The objectives were: (1) to measure and compare dry matter (DM) response of orchardgrass (Dactylis glomerata L.) to different amounts and application times of N fertilizer and liquid and solid cattle manure; and (2) to determine crop uptake of fertilizer and manure N. Fertilizer and liquid and solid manure were applied to the soil surface annually in amounts of 150, 300 or 450 kg N ha⁻¹ in one, two or four equal applications. Orchardgrass dry matter production increased over the entire range of N amounts from all sources. Yields varied from approximately 2500 kg DM ha⁻¹ for control plots (0 kg N) to 10600 kg for plots receiving 450 kg N ha⁻¹ either as fertilizer or liquid manure. Crop response to liquid manure application was greater in year one with abundant rainfall than in year two with dry conditions during most of the growing season, whereas crop response to solid manure application improved in the second year, due to the availability of residual organic N. Orchardgrass was more sensitive to the timing of fertilizer N application than to manure N application. Despite the large differences in weather patterns experienced during this study, analysis of application patterns indicated that manure could be applied throughout the growing season to crop stubble (post-harvest) with comparable rates of uptake overall. N uptake in control plots averaged 56 kg N ha⁻¹ for both years, compared to 340 kg N ha ⁻¹ for fertilizer plots, 250 kg N ha ⁻¹ for liquid manure plots and 190 kg N ha⁻¹ for solid manure plots receiving 450 kg total N ha ⁻¹.