DM Ha-1 Research Articles

Functional and mechanistic assessment of plant-available soil phosphorus greatly improved the multisite diagnosis of maize yield response

Context or problemPlant-available soil phosphorus (P) is commonly assessed by chemical extractions with the purpose of diagnosing and advising fertilizer P application. However, for a given crop, this approach only poorly predicts yields obtained from several experimental sites. To solve this major drawback, a functional and mechanistic evaluation has been developed to mimic dominant processes involved in the absorption of phosphate ions. Objective or research questionIn this study, we investigated the predictive ability of a mechanistic approach to diagnose maize (Zea mays L.) yields, in comparison to the common Olsen's method (0.5 M bicarbonate solution). MethodsThe processes-based assessment consists of parameterizing relationships between amount of diffusible phosphate ions (Pr) at the solid-to-solution interface equilibrating the phosphate ions concentration in solution (CP) with time (t). We parameterized [Pr vs. (CP, t)] relationships for stored and archived soil samples (plough layer) of nine long-term field experiments (LTFEs) on increasing rates of P applications including the zero-P treatment (P0). LTFEs were located in different soils (Luvisol, Podzol, Arenosol, Calcosol) with large variations in physico-chemical properties. We also used LTFEs database of maize yields. ResultsThe CP values ranged from 0.02 to 3.86 mg P L−1 for 40 (LTFE×year of maize cropping) combinations. The (Pr=v×CPw×tp) equation closely described the [Pr vs. (CP, t)] datasets, with (v, w, p) parameters being soil specific. Maximum yields ranged from 5.5 to 14.7 t DM ha−1 depending on LTFEs and years. Yields decreased significantly only in P0, and did not differ for other P rates. The relationship between the relative maize yield and CP was sites-specific with CP thresholds to obtain a relative yield of 0.95 ranged from 0.07 to 0.88 mg P L−1 solution. Taking into account amounts of phosphate ions which balance CP by diffusion using (Pr=v×CPw×tp) equations, a single response curve is observed for the 9 LTFEs when the replenishment time is 1500 minutes (i.e. about one day). The critical CP thresholds closely correlated to the ability of the soil solid phase to buffer phosphate ions in solution. ConclusionsFor the 9 studied LTFEs on P fertilization, the [Pr vs. (CP, t)] relationships were more able to account for maize response curves than P extracted by Olsen method, improving the precision and reliability of the multisite diagnosis of maize yield response. Implications or significanceAs a result, P fertilization recommendations are more reliable regardless of soil type. Further progress could be gained by taking into account for the role of the soil layer beneath the plough layer.

Do rotation and fertilization practices shape weed communities and affect rice yield in low input rainfed agroecosystems in the Malagasy highlands?

Weeds are a major threat in tropical regions where climate conditions favor their growth and development. This is particularly true in low-input rice-based cropping systems in the Malagasy highlands, where weed management is mainly done by manual removal. Crop rotation is often promoted as an efficient way to control weed infestations, while the role of fertilization is more controversial. In this study, we compared rice monoculture to three rainfed rice-based two-year rotations: rice followed by groundnut, rice followed by sorghum-cowpea mixture, and rice followed by a velvet-bean crotalaria mixture. Each rotation was tested with two levels of fertilization (5 t DM ha−1 organic manure, sole or in combination with mineral fertilizer - 400 kg ha−1 NPK + 200 kg ha−1 urea). We assessed the effect of rotation and fertilization on weed composition, diversity, biomass and rice yield. Additionally, the farmers’ perception of weed harmfulness and the relation between their assessment of weed harmfulness and rice production was tested. Our results showed that weed biomass significantly decreased rice yield but only under the low fertilization level. The rotation of rice with the velvet bean-crotalaria mixture was efficient in reducing weed biomass, modified weed community composition and allowed to achieve the highest rice yield. A significant negative relationship was found between weed community harmfulness index and weed species richness. Yet, the lowest rice yield was observed under rice monoculture despite a higher species richness over years and under high fertilization level. The lack of significant correlation between the harmfulness index and the actual rice yield is probably because our index is partly based on farmer’s perception, and only on major weeds. More studies on tropical weed harmfulness are needed to support the design of ecologically intensified cropping systems.

Yield and nutritive value of Urochloa hybrids at different regrowth ages

Objective: To evaluate the productive behavior of Urochloa hybrids, depending on the regrowth age.
 Design/Methodology/Approach: The study was carried out under rainfed conditions during 2018. The Cayman, Mulato II, Convert 330, Cobra, Camello I, and Camello II hybrids were evaluated based on the regrowth age (2, 4, 6, 8, and 10 weeks). The following variables were evaluated: plant height (PH), total dry matter (TDM) yield, dry matter per leaf (DMl) yield, dry matter per stem (DMs) yield, crude protein content (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF). The data obtained were evaluated by means of a randomized complete block design with three repetitions, divided into plots: a large plot for the cultivars and small plot for the regrowth ages.
 Results: The Camello II cultivar obtained the highest TDM yields during the sixth and eighth weeks (4.15 and 6.35 t DM ha-1, respectively); however, during the tenth week, the yield was equal to the yield obtained with the Mulato II and Cayman cultivars (p<0.05). The highest DMl yield was obtained by the Mulato II cultivar during the sixth, eighth, and tenth weeks (3.37, 4.56, and 3.86 t DM ha-1, respectively). The Mulato II cultivar recorded the highest CP values during the second and fourth weeks (158 and 126 g kg-1, respectively); however, the Camello II cultivar obtained the highest CP values during the sixth, eighth, and tenth weeks (99, 95, and 87 g kg-1, respectively). The NDF and ADF values increased as the regrowth age increased: in the tenth week, the Camello II and Cobra cultivars obtained the highest NDF values, while the Camello II cultivar recorded the highest ADF value during the same period.
 Study Limitations/Implications: Urochloa cultivars were developed for their establishment in humid tropical conditions, where their productive performance is greater. However, in dry tropical conditions, the Cayman, Mulato II, and Cobra cultivars have had a better performance than other grasses —such as buffel grass (Pennisetum ciliare), which is used to feed ruminants. In this sense, other Urochloa cultivars (e.g., Camello I and Camello II), which have greater tolerance to droughts, show desirable forage characteristics, such as yield and forage quality.
 Findings/Conclusions: The cultivars with the best productive performance were Camello II, Mulato II, and Cayman.

Cover Crop Yield, Nutrient Storage and Release under Different Cropping Technologies in the Sustainable Agrosystems.

Due to short post-harvest seasons, it is not always possible to grow worthy cover crops (CCs). This research aims to clarify the impact of undersown red clover (Trifolium pratense L., RC) and post-sown white mustard (Sinapis alba L., WM) management on their biomass, accumulated nitrogen (N), phosphorus (P), and potassium (K) content and the nutrient release to subsequent main crops. During the study period, RC mass yields varied from 220 to 6590 kg ha-1 DM and those of WM from 210 to 5119 kg ha-1 DM. WM shoot biomass increased with the increase in rainfall in August and the average daily temperature of the post-harvest period. CC productivity and efficiency were higher when growing short-season spring barley than winter wheat. In the warm and rainy post-harvest period, undersown WM after winter wheat increased the biomass by 34.1% compared to post-harvest sowing. The application of straw (+N) increased the accumulation of nutrients in WM biomass. The intensive fertilization of the main crop had a negative effect on RC yield and NPK accumulation. RC shoot biomass was characterized by a higher N content and WM by a higher P concentration. Well-developed CCs could reduce soil mineral nitrogen content by 28.5-58.8% compared to a plot without CCs. Nutrient transfer to spring barley was dependent on the N content of CC biomass and the carbon and nitrogen ratio (C:N < 20). We conclude that CC growth and efficiency were enhanced by the investigated measures, and in interaction with meteorological conditions.

105 Botanical composition, yield, horse preference, and forage and soil nutrient values of grass pastures treated with different soil amendments

Forage is the foundation of a horse's diet, therefore, pasture management is critical to improve horse health and pasture productivity. The objective of this study was to evaluate botanical composition, horse preference, yield, and forage and soil nutrient values of pasture treated with horse manure, horse compost, commercial urea fertilizer, and a no amendment control. Researchers hypothesized soil amendments would increase soil nutrients and yield with minimal effects on botanical composition, preference and forage nutrient value. Replicated (n = 3) plots of established cool-season mixed grass pasture were 3 × 6 m and located in St. Paul, Minnesota. The soil was a Waukegan silt loam with a pH of 6.4 and 47 g kg–1 organic matter. Urea was applied based on initial soil test recommendations, 0.64 cm of compost was applied based on common recommendations, and manure was applied at a rate to represent horse manure deposition in May 2022. Sample collection and grazing periods occurred in May, June, July, August, and October 2022, each over a 2-d period. Botanical composition, average forage height and maturity, soil samples, forage samples, and forage yield were taken immediately before grazing. Horses were allowed to graze all plots for 4 h with preference visuallyassessed at 2- and 4 h post-grazing based on percent removal. Data were analyzed as a randomized complete block design using PROC MIXED in SAS with significance set at P ≤ 0.05. Season-long yield ranged from 2,690 to 3,363 kg DM ha-1 and did not differ across treatments (P > 0.05). Botanical composition differed across treatments with the control having the most weeds (32%) and the least amount of grass (62%) while manure treatments resulted in the most bare ground (11%; P ≤ 0.05). The soil nutrients magnesium and phosphate were highest in compost-treated plots and nitrate-nitrogen and sodium were highest in manure-treated plots (P ≤ 0.05). Forage nutrient content did not differ across treatments (P > 0.05). Horses did not prefer pasture treated with manure and only 15 and 33% of forage was consumed after 2 and 4 h, respectively (P ≤ 0.001). All other treatments averaged 53 and 78% removal after 2 and 4 h, respectively. Based on differences observed in botanical composition and horse preference, commercial fertilizer and compost appear to be the most beneficial soil amendments for horse pastures.

Productive characteristics and structure of Paiaguás grass pasture fertilized with wood ash in the Brazilian Cerrado

The use of wood ash as a fertilizer is a practice that helps in the management of soil fertility. Our objective was to evaluate the potential use of wood ash on structural and productive characteristics of paiaguás grass (Urochloa brizantha) pasture. The experiment was carried out at the Federal University of Rondonópolis, Brazilian Cerrado. Treatments were five wood ash doses: 0, 8, 16, 24, and 32 t ha-1 and two application strategies (wood ash incorporated into the soil and wood ash not-incorporated). Wood ash doses significantly affected (p&lt;0.05) the evaluated response variables. Forage yield ranged from (mean ± standard error) 6.98±0.34 to 8.99±0.53 t DM ha-1. The highest productivity (11.10±0.46 t DM ha-1) was obtained at a wood ash rate of 24 t ha-1. The leaf area index was also higher (9.39±1.02) in the 24 t ha-1 wood ash dose. On the other hand, the leaf/stem ratio decreased with the application rate of wood ash and varied from 1.41±0.05 to 1.09±0.07 in the absence of wood ash (dose 0) and at the highest dose, respectively. In general, wood ash positively influenced (p&lt;0.05) the structural characteristics and yield of U. brizantha cv. Paiaguás. Wood ash doses that provided the highest crop yield were between 16 and 24 t ha-1. The incorporation of wood ash into the soil increased pasture regrowth time. Therefore, it is recommended to apply wood ash superficially in established pastures.

Benefits of liquid urea and a microbial catalyst on biomass and the nutritional value of Mombasa grass

During 2019, an experiment was conducted at the Agricultural Experiment Station in Isabela (Puerto Rico) on an Oxisol with previously well-stablished stands of cv. Mombasa. This experiment assessed the effects of a microbial catalyst (MC) and liquid urea 22-0-0 (LU) at a rate of 168 kg ha-1 (in split applications), a mixture of LU+MC and a control on aboveground biomass, root biomass, nutritional value, nitrogen use efficiency and soil parameters on cv. Mombasa at 35-day (d) harvests during six harvests. The study was established in a completely randomized design with four replicates. The effects of LU and MC on belowground (root) biomass were determined by collecting samples in 1 m2 to determine the yield and chemical composition. Soil samples were collected at 15 cm depth using a soil corer at the first and 6th harvest from each plot to assess organic carbon (OC), total nitrogen (TN), pH, macronutrients, and cation exchange capacity (CEC). The results showed that aboveground biomass doubled using LU (2369 kg DM ha-1) compared to the control and MC (1100 kg DM ha-1). Crude protein (CP) was 10.1 % using LU. Neutral Detergent fiber was 70 % for the control, 74.2 % when LU was used, and around 40 % for acid detergent fiber (ADF) for any treatment. Overall, there were no significant effects of treatments on OC and organic matter percentages, P, N, Ca, Mg, and CEC. In conclusion, LU is an excellent source of N for Mombasa, but shorter harvest frequencies may be required to improve the fiber quality of Mombasa.

Highlighting the benefits of biological nitrogen fixation on agronomic, physiological, and nutritive value traits of brachiariagrass

The search for efficiency in forage-based systems has intensified in recent years, increasing the need to reduce environmental impacts of animal agriculture. Reducing the dependence on fossil fuels for nitrogen (N) input with the use of microorganisms (e.g., biological nitrogen fixation, BNF) and grass-legume mixed stands has become an important practice. The objective of this study was to evaluate N input strategies that affect the agronomic, physiological, and nutritive value traits of Ipyporã brachiariagrass (Brachiaria hybrid ‘BRS RB331 Ipyporã’) based on the use of mineral N fertilization (ammonium sulfate), bacterial inoculation (Azospirillum brasilense strains Ab-V5 and Ab-V6; CNPSo), and mixed stands with forage peanut (Arachis pintoi Krapov. & W.C. Greg. cv. BRS Mandobi) in the Amazon biome. The treatments were six N-input strategies: 1. pastures with no nitrogen fertilization (control); 2. fertilized with 80 kg N ha-1 season-1 (N); 3. inoculated with A. brasilense (Az); 4. fertilized with 80 kg N ha-1 season-1 + A. brasilense (N + Az); 5. mixed stand of Ipyporã brachiariagrass and forage peanut (Mix) and 6. mixed stand + A. brasilense (Mix+Az). The experimental period was from 20 January 2015–21 March 2017, covering three summer growing seasons. Forage was cut to a 12-cm stubble when average canopy height reached 25 cm. Annual forage accumulation (FA) was greater in N, Az, N + Az, and Mix+Az (averaged 7760 kg DM ha-1) than in Control and Mix (averaged 6485 kg DM ha-1). The FA measured in Az and Mix+Az was equivalent to applying 58 and 86 kg of N ha-1, respectively when compared with Control. The greatest leaf mass was measured in N, Az, N + Az, and Mix+Az (averaged 1475 kg DM ha-1). The Az and Mix+Az can be options to improve the sustainability of forage systems and maintain forage production while using renewable sources for nitrogen.

Sunflower response to nitrogen doses

The sunflower is an oilseed species, rustic, cultivated in different agroecosystems. The responses of cultivars to nitrogen fertilization vary according to the cultivar and environment. Therefore, this research aimed to evaluate the response of biometric characters of sunflower cv. Embrapa 122-V2000 under N doses. The experiment was carried out in a randomized block design with five treatments (0, 40, 80, 120 and 160 kg N ha-1) and four blocks. All characters were influenced (p&lt;0.05) by N doses, fitting to the quadratic model. The maximum values of plant height (1.68 m), stem diameter (22.71 mm), leaf area (423.41 cm2), capitulum diameter (15.22 cm), dry biomass yield (6,075.13 kg DM ha-1) and grains (2,982.89 kg ha-1), N use efficiency from biomass (80.3 kg kg-1) and grains (43.27 kg kg-1) close to 90 kg N ha-1, this dose being recommended for the edaphoclimatic conditions of the Agreste Meridional Region of Pernambuco, Brazil.

FORAGE YIELD AND COMPOSITION OF BLACK OAT IN MONOCULTURE AND IN ASSOCIATION WITH WINTER VETCH

Associated grass-legume pastures have advantages over grass monoculture; in order to evaluate them the association of black oat (Avena strigosa Schreb) with winter vetch (Vicia villosa Roth) was analysed. The objective of the study was to evaluate forage yield, the botanical, morphological, and chemical composition of black oat in monoculture and in association with winter vetch, at different crop heights and residual stubble heights. Eighteen treatments were evaluated in randomized complete blocks with divided plots. In large plots, the culture type (monoculture or association); and in small plots, nine harvest management options (combinations) of three crop heights (Ch: 40, 50 and 60 cm) and three residual stubble heights (Rsh: 8, 14 and 20 cm). Forage yield was higher (p ≤ 0.05) in Ch50-Rsh8, Ch60-Rsh8 and Ch60-Rsh14 during the second crop cycle, with an average 8555 kg DM ha-1. In monoculture and in association, more cuts were made (three to four) with Ch40-Rsh14 and Ch40-Rsh20 and fewer cuts (one to two) with Ch60-Rsh8, Ch60-Rsh14 and Ch60-Rsh20. Crude protein concentration was 19 % higher (p ≤ 0.05) in monoculture than in association (19.2 and 16.2 %); the highest concentrations (p ≤ 0.05) of crude protein were obtained in Ch40-Rsh8, Ch40-Rsh14 and Ch40-Rsh20 (average 20.5 %), and the lowest was recorded in Ch60-Rsh8 (13.2 %). The forage with the least neutral detergent fibre (p ≤ 0.05) was harvested in Ch40-Rsh8, Ch40-Rsh14 and Ch50-Rsh14 (average 43.4 %), and the highest (49.3 %) was obtained in Ch60-Rsh20. In monoculture and in association, a greater amount of forage was harvested, distributed in at least two harvests, with Ch of 50 and 60 cm in combination with 8 and 14 cm of Rsh. However, the forage did not have the best composition, due to higher concentrations of neutral detergent fibre and lower crude protein concentration.

VISTOCK: A simplified model for simulating grassland systems

This article presents the structure and results of a simplified model (VISTOCK) for simulating grass growth and water dynamics of grassland systems. The model, based on a process-based approach coupled with proximal (SKR 1800 2-Channel Light Sensor) and remote (Sentinel-2) NDVI-derived data for estimating LAI, simulates aboveground biomass (AGB), net primary production (NPP), evapotranspiration (ET), and the fraction of transpirable water in soil (FTSW). VISTOCK simulated a grassland system with few meteorological data (i.e., minimum and maximum daily temperatures, precipitation, global solar radiation), considering limitations to vegetation growth due to thermal and water stresses. It was calibrated for a natural alpine grassland in Italy (site T) during the most contrasting meteorological seasons of the dataset (2012, 2017, and 2018). It was then evaluated for the remaining years at site T (2013, 2014, 2015, and 2016) and for other two sites in Italy (sites B1, B2 and M) with different soil and climate conditions and diverse management strategies (2020 and 2021). VISTOCK accurately predicted AGB during the growing season (RMSE = 445, 240, 219, 365 kg DM ha-1 for T, M, B1, and B2, respectively) as well as for NPP, ET, and FSTW at site T. Simulation results suggest the ability of the model to simulate grassland in diverse environments with few inputs and parameters to be calibrated. The model’s simplified structure, combined with easy-to obtain input data and easy applicability, encourages its wider use for out- and/or upscaling and decision making.

187 Body Performance of Beef Steers Swathgrazing oat Monoculture or Forage-Blends During Winter Months

Abstract Extended grazing strategies have the potential to reduce beef winter-feeding costs. Beef producers can incorporate monoculture cereal crops in their winter swathgrazing programs, but recently, the use of polycrops (also known as intercrops or cover crops) is growing. There is little information about beef cattle body performance when swathgrazing forage blends during winter months. This study evaluated animal performance when swathgrazing oat monoculture or a polycrop blend (oat, turnip,canola and forage pea). Forage systems (treatment) were seeded on a 12-hectare site, further separated into 2-hectare paddocks. The paddocks were seeded in June and swathed in August at the hard dough stage for the oats. Forty-two crossbred steers were randomly allocated to one of two replicated (n=3) systems while balancing for body weight and breed composition. Body weights (BW) were determined over two consecutive days at the start and end of grazing, and at 2-wk intervals throughout the 86 d grazing period. Ultrasound backfat, rumpfat and intramuscular fat were collected at the start and end of the trial. At the start of the trial, two steers in each replicate group were fitted with rumen pH/temperature boluses. The biomass yield of the oat and polycrop were 6,225±651 and 4,867±471 kg DM ha-1, respectively, while mean regrowth for oat and polycrop were 177 and 1409 kg DM ha-1, respectively. Start-of-test BW (246, 247kg; P = 0.92), end-of-test BW (304, 303.5; P = 0.97), average daily gain (0.68, 0.74 kg d-1; P = 0.61), backfat change (0.53, 0.69 mm; P =0.65), rumpfat change (0.84,1.30 mm; P=0.14) and intramuscular fat change (-0.12, 0.14%; P=0.66) did not differ for steers assigned to oat and polycrop systems, respectively. Other measures were mean rumen temperatures (39.13oC, 38.96oC; P=0.03) and pH (6.76, 6.70; P=0.10) for the oat and polycrop respectively. These results suggest that polycrops may be an alternative in a swath grazing system during the winter months.

Forage yield of African star grass (Cynodon nlemfuensis Vanderyst) at different cut heights

Objective: To determine the effect of cutting height, season, and year on the forage yield of African Star grass (Cynodon nlemfuensis Vanderyst) in Loma Bonita, Oaxaca, México. Design/Methodology/Approach: A randomized block design was used in plots divided using a factorial arrangement and three replications. The treatments consisted of the combination of cutting heights, seasons, and years of evaluation with four repetitions. The following variables were taken into consideration: fresh and dry forage yield (kg ha-1), leaf weight (kg FM ha-1), stem weight (kg FM ha-1), dead material (kg ha-1), leaf-steam ratio, and total yield per hectare (kg ha-1). An analysis of variance was carried out and the means were compared using Tukey's test. Results: The cutting heights did not have an effect on the DM yield. The uniformity cut can be made between 7 and 10 cm. DM performance for the 6 characters evaluated was better in 2018 than in 2016. Study limitations/Implications: Applying dolomite calcium to increase soil pH, N, P, and K levels under irrigated conditions could improve growth rates and DM production. Findings/Conclusions: Cutting heights did not have an impact on forage yield. The uniformity cut could be made at a 7-10 cm height. The rainy season had a higher dry matter yield (3,310 kg ha-1) than the dry season (1,902 kg DM ha-1) and the cold front season (1,914 kg DM ha-1).

Mathematical models to estimate forage production in southeastern Coahuila Mexico

Objective: Calibrate two non-linear models, in three intermediate triple hybrids, by theoretically comparing the accumulation of dry matter in relation to the days after sowing.&#x0D; Methodology: The cuts were every 14 days, from 30 to 170 das, and were adjusted to the Logistic and Richards models. The experimental design was a randomized block, with three replications.&#x0D; Results: The models explained most of the total dry matter yield in corn, observed in the field at 83%. The best fit model was the logistic model in cultivar AN447 and the Richards model in cultivar A7573, both with R2=0.98. The maximum yield simulated with the Richards model was shown in AN447 with 22,616 kg DM ha-1 and the lowest in AN388 with 10,970 kg DM ha-1.&#x0D; Limitations/Implications: Tests of other models in the same conditions and in other environmental conditions with the models under study.&#x0D; Conclusion: The Logistic model allows to simulate with greater precision the yield of dry matter in corn, by using the days after planting as an independent variable.

Yield, intercepted radiation and morphology of crotalaria (Crotalaria juncea L.) at different densities

Objetive: The objective of this study was to evaluate the yield, intercepted radiation and morphology of crotalaria (Crotalaria juncea L.) at different planting densities, in the dry tropics of the state of Guerrero, Mexico.&#x0D; Desing / Methodology / Approach: The treatments were: four planting densities at 400,000, 200,000, 100,000 plants ha-1 and a stream. A growth analysis was also evaluated at 30, 38, 45, 52, 60, 68 and 75 days of growth, understanding that the pod was fully developed. The variables evaluated were: dry matter yield, intercepted radiation and morphological composition.&#x0D; Results: The dry matter yield, regardless of the cutting age, was obtained in descending order at the planting densities of: 400,000 ˃ chorrillo ˃ 200,000 ˃ 100,000 plants ha-1 with 19,837, 17,918, 8,786 and 4,074 kg DM ha-1,&#x0D; Study Limitations / Implications: In the tropics it is necessary to broaden the panorama with the producers, in the use of forage legumes to improve the feeding of cattle.&#x0D; Findings / Conclusions: It is recommended to sow at a sowing density of 400,000 plants ha-1 and to cut after 45 days of growth in crotalaria since it is when the best structural characteristics of the meadow and 95% of intercepted radiation are found

Growth rate, leaf:stem ratio and height in crotalaria (Crotalaria juncea L.) planted at different densities

Objetive: To evaluate the growth rate, leaf:stem ratio and height of crotalaria plants (Crotalaria juncea L.), cultivated at different densities, in the dry tropics of the state of Guerrero, Mexico.&#x0D; Desing / Methodology / Approach: The treatments were: four planting densities at 400,000, 200,000, 100,000 plants ha-1 and trickling. A growth analysis was also evaluated at 30, 38, 45, 52, 60, 68 and 75 days of growth, including that the pod was fully developed. The variables evaluated were: growth rate, leaf:stem ratio and plant height.&#x0D; Results: The best growth rate was found at a density of 400,000 plants ha-1, at 75 days of development, with 577 kg DM ha-1 d-1; similar to plant height, which at this density presented 281 cm. Contrary to the leaf:stem ratio, which was greater than 30 days. Regardless of age, a descending behavior was found in the following order: 100,000 ˃ chorrillo ˃ 200,000 ˃ 400,000 plants ha-1 with 0.65, 0.60, 0.59 and 0.55 (p &lt; 0.05).&#x0D; Study Limitations / Implications: This study is essential for future research because these variables have not been evaluated in this crop; being important for forage production.&#x0D; Findings / Conclusions: It is recommended to sow at a density of 400,000 plants ha-1, finding a higher leaf:stem ratio at 30 days of development and a plant height at day 75, when pod production also begins

Establecimiento de gramíneas forrajeras tropicales en el bioma del Cerrado

This study was carried out to evaluate the time for the establishment of tropical forage grasses in the “Cerrado” biome, based on morphogenetic and structural traits. Three Brachiaria brizantha (Syn. Urochloa brizantha) cultivars (Paiaguás, Ipyporã and Marandu) and two Panicum maximum (Syn. Megathyrsus maximus) cultivars (Quênia and Tamani) were distributed in a randomized-block design with four replicates. Morphogenetic and structural traits of the pasture were assessed from d 35 to d 65 after sowing, at seven-day interval. Canopy height rose linearly with the establishment period, in all cultivars. In the Megathyrsus cultivars, tiller density decreased as the experimental period progressed, whereas the number of tillers in the Urochloa cultivars increased. The cultivars Ipyporã and Marandu had the highest leaf appearance rates. The lowest leaf elongation rates occurred in the cultivars Paiaguás, Ipyporã and Tamani, and the highest elongation rates in cv. Quênia. As a result, cv. Quênia showed the highest values of final leaf length (64.9 cm) and leaf blade mass (3,352.9 kg DM ha-1). The higher senescence rate of cv. Tamani (2.1 cm tiller-1 d-1) resulted in the highest percentage of dead material (1,815.5 kg ha-1) being found in the herbage mass of this cultivar. Cultivars Paiaguás, Marandu and Tamani were established at 44 d, whereas cv. Quênia and Ipyporã were established at 51 and 58 d after sowing, respectively, in the Brazilian Cerrado.

Cover crops biomass yield grown as a 2nd summer crop in relation to sowing periods

The aim of this study was to evaluate cover crop precocity and biomass yield growth as a 2nd summer crop after soybean at different sowing periods (January 2nd; February 2nd and March 2nd at 2019 and January 27th and March 3rd at 2020). Experiment was laid out as a randomized block design in a 3x3 factorial for each sowing period, in the 2019 and 2020 off-seasons, being factor A represented by the cover crops (Urochloa brizantha cultivar Xaraés, Crotalaria juncea cultivar IAC-KR-1 and Pennisetum glaucum cultivar ANm 38,) and factor B by the evaluation periods along cover crops development cycle. There was an interaction between cover crops and evaluation period for plant height and dry matter yield for both years. C. juncea and P. glaucum showed faster growth, regardless of the evaluation period and sowing periods, compared to U. brizantha in both years. Cover crop biomass yield reduced as sowing period is delayed from January to March to an extend that P. glaucum yield dropped from 14.6 to 4.2 t DM ha-1 at 2019 and from 14.4 to 6.9 t DM ha-1 at 2020 as a result shorter photoperiod and lower temperature. The same was noticed to U. brizantha and C. juncea which showed yields of 11.676 and 8.800 and 2.220 and 2.555 kg ha-1 at April 29th of 2019 and 12.507 and 7.812 and 3.041 and 2.346 kg DM ha-1 at June 18th 2020 respectively for January and March sowing periods. U. brizantha and C. juncea are more viable 90 days, while P. glaucum showed the fastest dry matter accumulation rate. All species are viable due to the benefits they provide to the productive system, which becomes more diversified and therefore more sustainable

Effects of atmospheric nitrogen deposition on productivity and growth allocation. First results of a long-term experiment in a pre-alpine beech forest

Atmospheric nitrogen deposition is an important global change driver, potentially affecting forest health and productivity. In order to evaluate the potential effects on tree growth and above-ground biomass production in southern European conditions, a long-term manipulation experiment was carried out in a prealpine beech forest (Pian Cansiglio, BL). Four treatments are compared: (i) control, (ii) moderate soil fertilization, (iii) high soil fertilization (iv) and moderate above canopy fertilization. Results, 7 years into the experiment, do not show any effect of soil fertilization treatments on the monitored parameters, but show instead positive effects of the canopy fertilization on the allocation of resources to the canopy and on the production of leaf biomass, with values that in 2021 exceeded those observed in the control treatment by 0.72 Mg DM ha-1. The contribution of N due to atmospheric deposition does not seem to decrease the growth of pre-alpine beech forests in the short term, but could substantially alter their ecological dynamics.

35 Herbage Accumulation and Nutritive Value of Legume-grass Baleage: A Comparison of Alfalfa-bermudagrass and Red Clover-bermudagrass in the Southeast

Abstract When interseeded into bermudagrass (Cynodon dactylon), alfalfa (Medicago sativa) has shown to increase herbage accumulation and improve forage nutritive value in Southern forage systems. However, data is limited on biennial red clover (Trifolium pratense) when interseeded into bermudagrass in the same manner. Therefore, a 2-yr evaluation was implemented in Tifton, GA to evaluate the herbage accumulation and nutritive value of annually seeded ‘Barduro’ red clover interseeded into ‘Tifton 85’ bermudagrass (CLO) to an existing stand of ‘Bulldog 805’ alfalfa interseed into ‘Tifton 85’ bermudagrass (ALF) (est. in 2016) when harvested as baleage. Treatments were randomly assigned in a randomized complete block design (2 treatments, 5 reps) to 0.2-ha plots and CLO treatments were established in winter of each year prior to evaluation. Plots were harvested once legume component reached early bloom stage (10%) every 28-35 d, baled at 40 to 60% moisture, cored for analysis, and individually wrapped. Harvested plots were evaluated for herbage accumulation, botanical composition, and nutritional value. Data were analyzed using the MIXED procedure of SAS as repeated measurements with the fixed effect of treatment, time, and their interactions, and random effect of block. Plot was considered the experimental unit. For both years ALF (Y1=1,753 and Y2=2,158 kg of DM ha-1, respectively) had a greater (P ≤ 0.048) herbage accumulation when compared to CLO (Y1=1,165 and Y2=1,946 kg of DM ha-1, respectively). Nutritive value was similar (P ≥ 0.122) for both treatments. Where ALF and CLO average 17.4, 50.7, 32.4, 63.2% (CP, NDF, ADF, TDN, respectively) with a SEM ≤ 0.943%. Both mixtures had similar nutritive value; therefore, adding legumes into bermudagrass can improve forage nutritive value. However, alfalfa-bermudagrass mixture had a greater yield in both years. Annually seeded red-clover bermudagrass mixtures provide an opportunity to produce baleage with similar nutritional value to alfalfa-bermudagrass but lower yielding.