Soil Science Commons^™

Effects Of Climate Change On Grassland Production In Switzerland, J Fuhrer, M Riedo

IGC Proceedings (1997-2023)

A mechanistic model for productive grassland was used to simulate annual dry matter yield in relation to fluxes of C, N, and water, and to test the sensitivity to climate change and to elevated [CO2] (2xCO2). Local weather scenarios were derived from the results of two General Circulation Models (GCM) by statistical down-scaling. Annual yield increased by a maximum of 10% without 2xCO2 effects, by 1-16% in response to 2xCO2, and by 6-24% with the combination of climate change and 2xCO2. Decreased evapotranspiration and increased water use efficiency in response to 2xCO2 were partially offset by climate change. The simulations …

Water Use Efficiency In Chilean And Argentine Humid Temperate Grass-Legume Pastures, H G. Landi, M H. Wade, V Garcia De Cortazar, D E. Dalla Valle

IGC Proceedings (1997-2023)

At two sites in Argentina and Chile five levels of water input were applied to four sown pastures of varying ages during spring and summer. The pastures consisted principally of C3 grasses and legumes, some of which were sown such as Lolium perenne, Trifolium repens, Dactylis glomerata. Dry matter (DM) production was measured and related to the estimated total evapotranspiration (ET): responses were both highly linear. Both responses to ET and absolute yields were higher at the Argentinian than at the Chilean site: respectively 10.7 and 15.2 kg DM/mm water evapotranspired. Nevertheless the calculated indices of sensitivity (Ky) of Doorenbos …

Mechanistic Modelling Of Grassland Energy Balance, G D. Buchan, B Main, B A. Mckenzie

IGC Proceedings (1997-2023)

No abstract provided.

Palatability Of Alfalfa (Medicago Sativa L.) And Orchard Grass (Dactylis Glomerata L.) Silages, R. D. Améndola-Massiotti, J. A. Burgueño, M. Concepción, L. Cruz

IGC Proceedings (1997-2023)

The objective was to compare palatability with different methodologies for characterizing silages at Chapingo Autonomous University, México. Eight silages were used resulting from an experiment which evaluated effects of cutting time (08:00 and 14:00), time of wilting (0, 1 and 2 h) and use of lactic bacteria inoculant on properties of alfalfa (Medicago sativa L.) and orchard grass (Dactylis glomerata L.) silages. Organoleptic properties (odor, color, texture, moisture) were assessed by trained observers, using as categories: excellent, good, fair and poor. Dry matter content, CO₂ rate of production and pH were also measured. For the evaluation of …

Evapotranspiration Of Rewetted And Drained Fen Soils With Grass – Long Term Lysimeter Studies, M. Pesch, J. Hoysagk, F. Eulenstein, A. Behrendt

IGC Proceedings (1997-2023)

In the context of reducing greenhouse gas (GHG) emissions to combat climate change, rewetting of peatlands is of particular importance. High groundwater levels covering organic matter in the soil prevent its oxidation to CO₂. The amount of water needed to allow the rewetting of peatlands can be determined in lysimeter studies.

The evapotranspiration in fens depends essentially on the groundwater table, the vegetation (transpirational active biomass) and the saturation deficit of the atmosphere. After rewetting, these factors can lead to an evapotranspiration of 1000 l m^-2 a^-1 and even 2000 l m^-2 a^-1 in …

Effect Of Timing And Intensity Of Drought On Perennial Ryegrass Seed Yield, R. J. Martin, R. N. Gillespie, S. Maley

IGC Proceedings (1997-2023)

Perennial ryegrass seed worth about $50 million is produced annually in Canterbury, New Zealand (Rowarth 1998). Ryegrass seed production in New Zealand is often affected by drought, reducing both seed number and seed size (Rolston et al., 1994). Irrigation management recommendations are not currently available for farmers growing ryegrass seed crops. To quantify the effect of water stress on perennial ryegrass seed yield, we carried out an experiment in a rainshelter where rainfall was excluded from experimental plots otherwise exposed to normal weather (Martin et al., 1990).

Increasing Precipitation Decreases Water Use Efficiency Of Alfalfa (Medicago Sativa L.) In A Semiarid Region, H. Ni, H. K. Chu, X. F. Lai, J. Q. Deng, Yuying Shen

IGC Proceedings (1997-2023)

Alfalfa (Medicago sativa L.) plays an important role within the integrated farming systems in Northwestern Loess Plateau of China, because of its traits on a high productivity, prolonged growing season, and excellent nutritive value. However, water use efficiency (WUE) is a crucial indicator for forage production under different water conditions in the semiarid regions. To explore the responses of alfalfa growth and water use to precipitation variability, we set precipitation shelters to manipulate precipitation scenario as 30% precipitation increased (P+30), normal precipitation (CK), and 30% precipitation decreased (P-30) with the measurement of dry matter yield and soil water content. …

Water-Use Efficiency And Infiltration Under Different Rangeland Conditions And Cultivation In A Semi-Arid Climate Of South Africa, Hennie A. Snyman

IGC Proceedings (1997-2023)

The objective of this study was to determine the impact of rangeland in different botanical composition classes (good, moderate and poor), on water-use efficiency (WUE: crude protein produced per unit of evapotranspiration) and soilwater content. The same measurements were also made on an undisturbed bare soil surface and soil cultivated twice per annum. Evapotranspiration was determined by quantifying the soil-water balance equation with the aid of runoff plots and soil-water content measurements done by a neutron hydroprobe. Water-use efficiency declined significantly (P ≤ 0.01) with rangeland degradation. Rangeland in good condition averaged a WUE of 0.28 kg crude protein ha …

Exploring Water Use And Production Dynamics Of Indigenous Protected Sikumi Forest In South Western Zimbabwe, O. Gwate

IGC Proceedings (1997-2023)

Monitoring changes in carbon and water vapour fluxes over a landscape helps in understanding ecosystem functioning and improves vegetation management. To understand potential shifts in ecosystem functioning, MoDerate Resolution Imaging Spectroradiometer (MODIS) evapotranspiration (ET), net photosynthesis, gross primary production and net primary production data were explored in Sikumi forest dominated by three species clusters (Teak forest woodland, Miombo woodland and savannah, and Vachellia). Measures of ecosystem stability including water use efficiency (WUE), rainfall use efficiency (RUE), evaporative index, and carbon use efficiency (CUE) were assessed for trends and step changes together with rainfall and evapotranspiration data. Miombo woodland and …

Partitioning Of Evapotranspiration In Four Grassland Ecosystems With A Two Source Model, Zhongmin Hu, Guirui Yu, Xiaomin Sun

IGC Proceedings (1997-2023)

No abstract provided.

Water Use Efficiency And Evapotranspiration Of Hybrid Napier (Pennisetum Purpureum X P. Americanum) Under Semi-Arid Indian Region, J. B. Singh, Rajiv K. Agrawal, Pradeep Behari

IGC Proceedings (1997-2023)

Napier bajra hybrid (Pennisetum glaucum x P. purpureum) is a highly valued for its abundant quality forage, round the year fodder availability, regenerative ability and suitability to silage and hay making. It yields upto 110-120 t/ha fresh fodder as sole crop. Though, it requires moist regimes for optimum growth, but it can withstand drought for a short spell and regenerate with rains. It contains 8.7-10.2 % crude protein, 28-30.5% crude fibre and 10-11.5 % ash on dry matter basis (Agrawal et al., 2001). The hybrid napier has wider adaptability and is grown all over the country, …

The Influence Of Geo-Morphological Landscape Patterns On Vegetation Characteristics In Tajikistan Grasslands, Mounir Louhaichi, Aziz Nubekov, Abdulla Madaminov, Barbara Rischkowsky

IGC Proceedings (1997-2023)

Grassland ecosystems are affected by a combination of physical and environmental factors, as well as by grazing and human induced activities. The primary objective of this study was to examine the influence of geo-morphological landscape patterns on vegetation characteristics in Tajikistan where two sites were selected. The vegetation sampling took place in spring and fall. Vegetation characteristics were assessed using the line intercept method for vegetation cover and species composition and quadrat sampling for biomass production. An ANOVA using replicated trials in complete block design was used to determine the relationship between aspect and vegetation characteristics. Treatments included location (site), …