Agricultural Science Commons^™

Growth Responses Of Acacia Angustissima To Vesicular-Arbuscular Mycorrhizal Inoculation, N. Lucena Costa, Valdinei T. Paulino, T. S. Paulino

IGC Proceedings (1977-2023)

The response of Acacia angustissima to VAM species (Acaulospora laevis, A. muricata, Entrophosphora colombiana, Glomus mosseae, G. fasciculatum, G. macrocarpum, G. etunicatum, Gigaspora margarita, G. gigantea and Scutellospora heterogama) was evaluated under greenhouse conditions, in a P-deficient clayey Oxisol of pH 5.5. The soil was sterilized at 110^oC for one hour each day for three days and reinoculated with a soil microbial suspension free of mycorrhizal fungi spores. The several VAM fungi were effective in increasing DM yield, nodulation, and N and P uptake of A. angustissima plants. The most efficient species were E. colombiana, A. …

The Fertilization Of Forage Grasses With Phosphorus In The Cerrado Area Of Uberaba-Mg, Brazil, I. F. Andrade, M. A. Oliveira

IGC Proceedings (1977-2023)

Using an area of Cerrado at the EPAMIG Experimental Station in Uberaba - MG, it was studied the response of four forage grasses to phosphorus application. It was used the grasses: Andropogon gayanus, Brachiaria brizantha, Hyparrhenia rufa, and Panicum maximum. The phosphorus fertilizer used was a yoorin termophosphate and the doses were: 0, 50, 100, 150, and 200 kg/ha of P₂O₅. The experimental design was a randomized complete block with three replications. Each experimental unit measured 6x8m and the measured parameters were: dry matter production, protein production, percentage of dry matter, and protein, and …

Alfalfa Response To Phosphorus Sources Associated With The Application Of Liming And Gypsum-Shoot Numbers, P. Sarmento, M. Corsi, F. P. Campos

IGC Proceedings (1977-2023)

Alfalfa (Medicago sativa L.) was grown in a Typic Mapluolox soil with triple superphosphate (TS), Gafsa phosphate (GP) and GP with gypsum (GP + G). Three rates of phosphorus application were used 50, 100 and 200 mg P dm^-3, before and after liming. Alfalfa was harvested three times. Basal and axillary shoot numbers in alfalfa increased with increasing phosphorus rates. Shoots were produced in higher number with GP in comparison with TS. GP + G resulted in higher basal shoot number than GP. However, there was no gypsum effect on axillary shoot numbers. Liming before or after …

Soil Nitrate Level Variation Under Intensive Nitrogen Fertilized Coastcross Pasture, O. Primavesi, A. C. Primavesi, L. A. Corrêa, H. Cantarella, A. G. Silva

IGC Proceedings (1977-2023)

Nitrate levels in soil profile after the first N application on coastcross pasture, grown on a dark red latosol (Hapludox), in São Carlos, SP, Brazil, under tropical altitude climate, were measured at 7-day intervals, to monitor possible losses in depth. Soil nitrate rates varied with high rates of N-ammonium nitrate (200 kg ha^-1 per cutting) in surface layers. Danger of environmental impact was low in the studied conditions.

Saturated Field Hydraulic Conductivity Variation In Intensively Managed Tropical Pastures, O. Primavesi, A. C. Primavesi, S. R. Vieira

IGC Proceedings (1977-2023)

Saturated field hydraulic conductivity was measured, using a Guelph permeameter, at the depths of 10, 20 and 60 cm, to verify the effect of intensively managed, compared to extensively managed ones, beef cattle production systems on pastures grown on three soils (Hapludox, Eutrudox, Paleudalf), in São Carlos, SP, Brazil, under tropical altitude climate. Significant differences occurred within depths (P < 0.05). However, differences decreased with years and, therefore, differences among soils and between management systems were also reduced. Highest mean conductivity values occurred at 60-cm depth and at the extensively managed sward on the sandy Hapludox. Intensively managed Paleudalf showed high resistance to reduction of conductivity at 10-cm depth. A general year effect appeared claiming for more studies on this matter.

The Effect Of Feed Supplementation And Sward Characteristics On The Ingestive Behaviour Of Grazing Ewes, C. H. E. C. Poli, Marta G. Da Rocha, C. C. Pires, Luis H. E. Farinatti, D. Montagner, G. Bica

IGC Proceedings (1977-2023)

The objective of this study was to assess the effect of protein/energy supplementation and sward physical characteristics on grazing behaviour of lactating ewes grazing Italian ryegrass (Lolium multiflorum Lam.). The experiment was carried out in the spring of 1999 at the Universidade Federal de Santa Maria. The grazing behaviour was assessed in two periods: 2 and 3 September, and 8 and 9 October of 1999, using a group of twelve yearling ewes. Groups of four ewes were either supplemented (with 1% of the animals live weight) with soybean meal (protein source), with corn (energy source) or not supplemented. The …

The Effect Of Sward Surface Height On Sheep Grazing Activities, Paulo C. De F. Carvalho, E. O. Silveira, L. S. Pontes, C. H. E. C. Poli, A. B. Soares, H. M. M. Ribeiro Filho

IGC Proceedings (1977-2023)

The objective of this study was to assess the effect of Italian ryegrass (Lolium multiflorum Lam.) sward height on grazing activities. The experiment was carried out at the Research Station of Universidade Federal do Rio Grande do Sul, Brazil. Yearling no-castrated male lambs behavior was assessed in terms of diurnal grazing, ruminating and idling time in three periods: 27 September 11 and 25 October. Sward surface height was monitored using a sward stick and samples of 0.25 m² were cut to ground level to estimate herbage and leaf lamina mass. The experiment was carried out in a randomised …

Grazing Behavior And Activity Patterns By Free-Grazing Cattle In The Pantanal Region, S. A. Santos, C. Costa, L. V. A. S. Chalita, A. Pott, J. M. Alvarez, A. G. Ortiz

IGC Proceedings (1977-2023)

A study of habitat selection and habitat use by free-grazing cattle was conducted in the Pantanal, from October 1997 to September 1999. Observation periods lasted 13 hours per day during three days in each month. The location and activity duration of each group of animals was recorded by continuous sampling. Rumination, walking and resting times were affected (P < 0,05) by interaction between month and year and grazing time differed (P < 0,05) only between months. On average, cows spent 54.9, 29.6, 10.6 and 4.9% of their diurnal hours grazing, ruminating, walking and resting, respectively. The grazing time spent in each landscape unit was influenced (P < 0,05) by interaction between month and year. The cows exploited more intensively the temporary ponds in 97/98 (26 min ha^-1) and the edge of ponds in 98/99 (23.2 min ha^-1). Therefore, the adequate grazing management practice may not follow fixed rules for the Pantanal.

Impact Of Overseeding Cool-Season Annual Forages On Spring Regrowth Of Tifton 85 Bermudagrass, Ricardo A. Reis, Lynn E. Sollenberger, D. Urbano

IGC Proceedings (1977-2023)

Field observations have shown stand reduction and slow spring regrowth of Tifton 85 bermudagrass (Cynodon spp.) pastures overseeded with temperate forages for grazing during the cool season. This experiment compared the effect of cool-season management programs, including overseeding and use of different grazing treatments, on productivity of Tifton 85 the following warm season. There were seven treatments: four were bermudagrass overseeded with a cool-season annual forage mixture (two grasses and two legumes) and grazed differentially, and three were bermudagrass controls with differences in amount of residual stubble remaining at beginning of autumn. There was only a slight delay in …

Influence Of Grazing Frequency On Biomass Production Using Several Selected Tropical Grasses, P. Mislevy, F. G. Martin, F. M. Pate, N. F. G. Rethman

IGC Proceedings (1977-2023)

To provide commercial growers with forage grasses that produce well throughout the year, there is a constant need for screening and testing new germplasm. Two rhodesgrasses (Chloris gayana cv. Rhods and Callide), four stargrasses (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. Florona, Zimbabwe, Okeechobee, and Rhodesian No. 2), one bermudagrass (C. dactylon var. dactylon cv. Jiggs), and one creeping signalgrass (Brachiaria humidicola CIAT 6369) were tested under a mob-grazing system. Dry biomass yield increased linearly as grazing frequency (GF) was delayed from 2 to 7 weeks. The cultivars, Florona, Zimbabwe and Okeechobee stargrasses and Jiggs bermudagrass, yielded …

Variation Of Herbage Intake (Hi) From Upland Pasture, As Influenced By The Grazing Initiation Date (Gid), D. Maæešiæ, M. Kneževiæ, Z. Štafa, J. Leto

IGC Proceedings (1977-2023)

Studies were conducted on an experimental pasture belonging to the Arrhenatherethum medioeur. and Lolio-Cynosureth. assoc. with D. glomerata, L. perenne and T. repens as main species, at an altitude of 680 m. Four equally sized paddocks (0.3 ha) were grazed by 10 Charolais heifers. The differences in total herbage dry matter intake (HDMI) between the four paddocks with different grazing initiation dates (GID) were significant (P < 0.05). The results of this experiment show that in order to achieve a higher HDMI and better herbage utilization an earlier initiation of grazing is recommended. That is, grazing should commence when the sward height is about 15 cm.

Nutritive Value Of Double Cropped Corn For Ruminant Production, D. Vaz Martins, A. Fassio

IGC Proceedings (1977-2023)

The viability of double cropping corn (Zea mays L.) in Uruguay, germplasm combination, dry matter yield and nutritive value were evaluated. An early (E) maturing hybrid, an early to medium (E-M) one and an E-M variety were planted as spring crops. One E-M hybrid, one medium to late (M-L) hybrid and a late (L) variety were planted as a second crop. PVC laboratory scale silo of the spring crop and the whole plant of the summer crop were chemically analyzed. The nutritive value of the silages were related to plant maturity stage. No differences were detected in nutritive value among …

Two-Dimensional Monitoring Of Spatial Distribution Of Herbage Mass Under Grazing, S. Ogura, Masahiko Hirata

IGC Proceedings (1977-2023)

Spatial distribution of herbage mass (HM) was monitored two-dimensionally during the grazing season (from May to November) in a bahiagrass pasture rotationally grazed by cattle. An electronic capacitance probe was used to estimate HM in 1464 permanent positions (50 × 50 cm) whose centres formed 1.5 × 1.5 m grids in the central 90 × 34.5 m area of the pasture. The highest mean HM was in September and October, while coefficient of variation in November. The two-dimensional charting of HM showed almost stable spatial patterns throughout the grazing season, with some patches of high HM appearing and disappearing. The …

The Effect Of Herbage Mass Of A Pasture On The Spatially Heterogeneous Grazing By Cattle, S. Ogura, Masahiko Hirata

IGC Proceedings (1977-2023)

To obtain information on spatially heterogeneous grazing by large herbivores at different time scales, spatial distribution of herbage mass and rate of defoliation was investigated on a bahiagrass (Paspalum notatum Flügge) pasture grazed by cattle during 4 to 5-day grazing periods in May, August and October. Pre-grazing herbage mass (M_pre) showed decreasing mean values and increasing spatial heterogeneity with the progress of grazing in all grazing periods, while the rate of defoliation showed inconsistent changes with season. Spatial distribution of the rate of defoliation was always more heterogeneous than that of M_pre. The correlation coefficient …

Relationships Between Spatial Distributions Of Herbage Mass And Utilization In A Pasture Progressively Grazed By Cattle, Masahiko Hirata, S. Ogura

IGC Proceedings (1977-2023)

To obtain some information about the mechanisms behind the spatially heterogeneous grazing of a pasture by large herbivores, the relationships between the spatial distributions of herbage mass, herbage consumption and ingestive behavior were investigated on a bahiagrass (Paspalum notatum Flügge) pasture during a 6-day grazing period with cattle. The animals almost always consumed more herbage from locations with higher pre-grazing herbage masses, which was attributed to greater bite weights. It was suggested that the high spatial heterogeneity in the rate of defoliation was caused mainly by the spatial heterogeneity in both the bite weight and the number of visits …

A Machine Learning Interpretation Of The Contribution Of Foliar Fungicides To Soybean Yield In The North‐Central United States, Denis A. Shah, Thomas R. Butts, Spyridon Mourtzinis, Juan I. Rattalino Edreira, Patricio Grassini, Shawn P. Conley, Paul D. Esker

Department of Agronomy and Horticulture: Faculty Publications

Foliar fungicide usage in soybeans in the north-central United States increased steadily over the past two decades. An agronomically-interpretable machine learning framework was used to understand the importance of foliar fungicides relative to other factors associated with realized soybean yields, as reported by growers surveyed from 2014 to 2016. A database of 2738 spatially referenced fields (of which 30% had been sprayed with foliar fungicides) was fit to a random forest model explaining soybean yield. Latitude (a proxy for unmeasured agronomic factors) and sowing date were the two most important factors associated with yield. Foliar fungicides ranked 7th out of …

Adapting Tropical Forages To Low-Fertility Soils, Idupulapati M. Rao

IGC Proceedings (1977-2023)

Tropical forages growing in low-fertility acid soils usually increase the amount of dry matter partitioned to roots at the expense of shoot growth, but substantially different adaptive attributes to such soils have been found, both between and within species. By possessing the C₄ pathway of photosynthesis, grasses are more efficient than legumes in using N, Ca, and P, whereas legume roots are more efficient in extracting nutrients from low-fertility soils. Phosphorus uptake efficiency (mg of P uptake in shoot biomass per unit root length) of the legume Arachis pintoi is several times higher than that of the grass Brachiaria …

Adaptation Of Forage Species To Drought, D. J. Barker, J. R. Caradus

IGC Proceedings (1977-2023)

Variability in rainfall is the single greatest cause of variation in forage production for a given site. Current climate scenarios predict future annual rainfall to decrease at some geographic regions. The intensity of future rainfall is also predicted to increase at other regions, with the expectation of greater variability in soil moisture. The adaptation of forage species to drought is an issue that is likely to remain with us into the future.

Precise definitions are critical to water relations work, and imprecise use of terms has complicated comparisons of some studies on plant response to drought. Drought is a purely …

Spittlebugs: Bioecology, Host Plant Resistance And Advances In Ipm, José R. Valério, C. Cardona, D. C. Peck, G. Sotelo

IGC Proceedings (1977-2023)

Several species and genera of spittlebugs (Homoptera: Cercopidae) are economic pests of grasses in tropical America. These insects compete with grazing animals by reducing forage availability and quality. They may cause serious losses on millions of hectares of improved pastures based on cultivars of several species of Brachiaria (signal grasses). Except for the cultivar Marandu, most of the available commercial cultivars of Brachiaria are susceptible to spittlebugs. In spite of their economic importance, much research need to be done yet. Such insect-plant system encompasses a diverse group of spittlebug species, a diverse group of forage grass species, which are under …

Grassland Plant Diseases: Management And Control, S. Chakraborty

IGC Proceedings (1977-2023)

Grasslands cover 40% of the earth’s surface and support animal-based industries; maintain soil cover, watersheds and biodiversity; sequester atmospheric carbon for storage in the soil; and provide tourism and leisure income. Diseases continue to decrease herbage and seed yield and reduce nutritive value and palatability of grasslands to impact on animal health and productivity but realistic data on loss are hard to find. Although principles of disease management remain the same, strategies used in crop protection can not be directly applied to grasslands due to differences in heterogeneity, population size, density and spatial distribution and population continuity. Low per hectare …

Soil Carbon And Nitrogen Dynamics After Pasture Installation In The Amazon Region, C. C. Cerri, M. Bernoux, C. E. P. Cerri

IGC Proceedings (1977-2023)

The objective of this paper is to present the soil carbon (C) and nitrogen (N) dynamics in a chronosequence made of a forest and pastures of different ages established in a Oxisol in the Western Brazilian Amazon Basin. The results of soil Carbon and Nitrogen stocks and gases fluxes were discussed. Stable ¹³C isotopic technique was used to calculate for a determinate age of pasture installation, the proportion of soil C remaining from the forest system and the proportion of soil C introduced by the grasses of the pasture system. The C lost from the original pool under the …

Micronutrients In Grassland Production, U. C. Gupta, F. A. Monteiro, J. C. Werner

IGC Proceedings (1977-2023)

Micronutrients, also known as trace minerals, which chiefly include boron (B), molybdenum (Mo), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe), are required in extremely small quantities by crops and livestock. Their name, however, is not meant to imply their role is minor. Their lack, e.g., can cause serious crop production problems in forages and health disorders in livestock. This presentation includes the response of forage legumes and grasses to micronutrients, their deficiency and sufficiency levels in forages and their sufficiency levels in livestock. Forage legumes are more responsive to micronutrients, particularly B and Mo, than grasses. There are …

Pasture Seed Production Technology In Brazil, Ronaldo Pereira De Andrade

IGC Proceedings (1977-2023)

Efficient and low cost production systems, which rely on the use of cultivated pastures, are the basis of beef and milk production in Brazil. The success of these pasture-based systems would not be possible without the support of an aggressive and dynamic pasture seed production sector to supply the internal demand, which is estimated to be around 90000 tons per year. The market is dominated by grass species and among them, Brachiaria. brizantha cv. Marandu accounts for more than 80% of the total seed volume in the market. Seed production systems in Brazil vary from highly specialized to opportunistic accordingly …

Meeting The Changing Need For Herbage Seed Quality Assurance In The 21st Century, D. S. Loch, K. G. Boyce

IGC Proceedings (1977-2023)

Quality assurance is a key element in the herbage seed supply chain. The measurement and management of seed quality is discussed in terms of its four main parameters - genetic, physical, vital, and phytosanitary quality - which provide information on the expected performance of herbage seed when sown in the field. During the past century, seed quality management systems have evolved in response to national and regional differences in economic development, crop characteristics, merit testing, and the demands of international trade. The pace of change in the management of seed quality assurance has intensified in developed countries over the past …

Novel Grasses And Legumes Germplam: Advances And Perspectives For Tropical Zones, E. A. Pizarro

IGC Proceedings (1977-2023)

It has been the aim, in the present article, to bring together as much as possible scientific evidence and experience in new available germplasm for tropical zones.

The economic importance of the Brachiaria, Paspalum and Pennisetum grasses is well established. New germplasm has become available since 1980. This paper reviews evaluations of Brachiaria accessions in humid lowlands and savannas of tropical America. The selection criteria need to be revised. Also, it is necessary to expose the new material as early as possible to farmers in order to select new germplasm with high chances of adoption.

Within the genus Paspalum …

Temperate Forage Grass-Legume Mixtures: Advances And Perspectives, A. S. Laidlaw, N. Teuber

IGC Proceedings (1977-2023)

The paper summarises some of the advances which have been made a) in increasing understanding of the grass-legume association, especially grass-white clover, so that the association can be more predictably exploited and b) in overcoming limitations in the use of such mixtures. The contribution which forage legumes make to the N economy of mixtures is reviewed with estimates approaching 400 kg N ha^-1 for some. Uptake by grass of legume- derived N (N transfer) reduces soil mineral N levels and increases the proportion of fixed N in the total legume N relative to legume monoculture. Although N transfer also …

Effect Of Sources And Rates Of Nitrogen On Nutrients Extraction In Coastcross Pastures, A. C. Primavesi, O. Primavesi, L. De A. Corrêa, H. Cantarella, A. G. Da Silva, A. R. Freitas

IGC Proceedings (1977-2023)

The contents and the extraction of mineral nutrients were determined in a coastcross pasture established on a dark red latosol (Hapludox), in São Carlos, SP, Brazil, under tropical altitude climate, receiving five rates of urea and ammonium nitrate, applied on surface. There were differences (P< 0.05) among sources and rates of N. Nutrients extraction increased with the nitrogen levels. Especially high were total N (319 and 446 kg ha^-1) and K (341 and 467 kg ha^-1) extractions. When forage yield was high (treatment with 500 kg of N ha^-1) and for both fertilizers, macronutrients extraction was greater for K and N, followed by Ca, S, P and Mg. Micronutrients extraction occurred in the following decreasing order: Fe, Mn, …

Dry Matter Production Response Of Coastcross (Cynodon Dactylon (L.) Pears) To Sources And Rates Of Nitrogen, L. De A. Corrêa, H. Cantarella, A. C. Primavesi, O. Primavesi, A. R. Freitas, A. G. Da Silva, E. B. Pott

IGC Proceedings (1977-2023)

Dry matter production of a coastcross pasture grown on a dark red latosol (Hapludox), in São Carlos, São Paulo State, Brazil, under tropical altitude climate, was evaluated. The goal was to verify the efficiency of N rates as urea and ammonium nitrate: 0, 25, 50, 100 and 200 kg ha^-1 per cutting, in five periods. Both sources were equally efficient. The mean N rates, which produced 80% of maximum forage yield, were 78 and 58 kg N ha^-1, respectively, for urea and ammonium nitrate, and were related to dry matter yields of 2,769 and 3,347 kg ha …

Ammonia Losses By Volatilization From Coastcross Pasture Fertilized With Two Nitrogen Sources, H. Cantarella, L. De A. Corrêa, A. C. Primavesi, O. Primavesi, A. R. De Freitas, A. G. Da Silva

IGC Proceedings (1977-2023)

Ammonia losses by volatilization from five rates of urea or ammonium nitrate surfaceapplied to coastcross pasture, grown on a dark red latosol (Hapludox) in São Carlos, SP, Brazil, under tropical altitude climate, were measured. Volatilized ammonia was absorbed in traps placed on soil surface. The mean losses from urea applied after five successive cuttings of the grass were 15, 24, 34, and 40% for N rates of 25, 50, 100 and 200 kg N ha-1 per cutting, respectively.

Assessing The Effect Of N And P Supply On Dry Matter Yield Of Three Tropical Grasses, O. Topall, C. Jouany, M. Duru, P. Cruz

IGC Proceedings (1977-2023)

The objectives are to study the effects of N and P supply and their interaction, on herbage dry matter yield and nutrient status of three tropical grasses. In order to estimate direct and indirect effects of P supply we express above-ground dry matter production as a function of the herbage nutrient status obtained from plant analysis. Results show that in absence of N, the significant increase in P nutrition status has only moderate consequences on herbage production and suggest that both N and P are limitant for herbage growth. P fertilization results in significant increase in dry matter yield only …