Maize yields benefit from injected manure positioned in bands
Schroder, J.J. ; Vermeulen, G.D. ; Schoot, J.R. van der; Dijk, W. van; Huijsmans, J.F.M. ; Meuffels, G.J.H.M. ; Schans, D.A. van der - \ 2015
European Journal of Agronomy 64 (2015). - ISSN 1161-0301 - p. 29 - 36.
field-grown maize - zea-mays l - cattle slurry - mineral fertilizer - soil-temperature - silage maize - nitrogen - phosphorus - placement - netherlands
The use of positioned mineral fertilizer phosphorus (P) starters reduces the risk of yield penalties in maize production. However, it also increases the soil P surplus and attendant risk of P losses to the environment, in particular on farms with ample supplies of livestock manures. We examined whether routine applications of starter P can be refrained from if manure is injected in subsurface bands close to the anticipated position of the maize rows as an alternative to the conventional even injection at random lateral positions relative to the rows. Fourteen field experiments were executed on sandy soils in The Netherlands. In these experiments comparisons were made of the nitrogen (N) and P-concentrations in shoots and of dry matter (DM), N and P-yields over time, between evenly injected liquid manure (with and without starter P) and band-injected liquid manure. Silage yields of DM, N and P generally responded positively (P <0.05) to starter P applied at a rate of 9–31 kg per hectare where manure had been applied at rates of circa 120 kg N and circa 20 kg P per hectare, but less so when the manure was band-injected. This positive response to P was not reflected in the concentration of P in shoots. Positioning of manure via band-injection without extra starter P resulted in silage maize dry matter yields that were similar to yields after even injection combined with a P-starter. Band-injection improved the recovery of the N and P (P <0.05) supplied by the manure and reduced the soil surpluses of N and P. Planting maize close to bands where liquid manure had been injected, thus increased silage yields and contributed to a better balance between the inputs and outputs of plant nutrients.
Calonectria diseases on ornamental plants in Europe and the Mediterranean Basion: an overview
Vitale, A. ; Crous, P.W. ; Lombard, L. ; Polizzi, G. - \ 2013
Journal of Plant Pathology: rivista di patologia vegetale 95 (2013)3. - ISSN 1125-4653 - p. 463 - 476.
cylindrocladium-crotalariae microsclerotia - forest tree nurseries - 1st report - root-rot - leaf-spot - crown rot - feijoa-sellowiana - soil-temperature - mastic tree - damping-off
Species of Calonectria and their cylindrocladium-like asexual morphs are important plant pathogens of agronomic and forestry crops, especially in the tropical and subtropical regions of the world. Calonectria species have been associated with a wide range of disease symptoms on a large number of plant hosts. On horticultural crops, most records of Calonectria species come from the Northern Hemisphere, where they occur mainly in gardens and ornamental nurseries. In Europe and the Mediterranean basin, several species are widespread in nurseries and cause extensive damage to ornamental plants. In the past, identification of species was based on phenotypic characters and sexual compatibility using standardised media. More recently, morphological characteristics, phylogenetic studies (DNA sequence data of the ß-tubulin, histone H3 and translation elongation factor-1a gene regions) and mating studies have revealed the presence of several cryptic species complexes that were formerly treated as single Calonectria species. These studies resulted in the introduction of several new species. Other studies aimed at understanding environmental sustainability focused attention on soil solarisation and biological control as means for controlling these pathogens. The potential use of biological control agents (BCAs) and chemicals for controlling Calonectria-induced diseases has recently been addressed. In this review we discuss the Calonectria species detected in Europe and the Mediterranean basin, and the disease management strategies. In view of the mandatory implementation of integrated pest management (IPM) for all European countries by 2014, this paper provides basic information as a platform for the adaptation of more sustainable integrated measures to control Calonectria diseases in European nurseries.
Using FLUXNET data to improve models of springtime vegetation activity onset in forest ecosystems
Melaas, E. ; Richardson, A. ; Friedl, M. ; Dragoni, D. ; Gough, C. ; Herbst, M. ; Montagnani, L. ; Moors, E.J. - \ 2013
Agricultural and Forest Meteorology 171-172 (2013). - ISSN 0168-1923 - p. 46 - 56.
terrestrial biosphere model - deciduous forest - co2 exchange - temperate regions - soil-temperature - phenology model - carbon-dioxide - annual cycle - bud-burst - trees
Vegetation phenology is sensitive to climate change and variability, and is a first order control on the carbon budget of forest ecosystems. Robust representation of phenology is therefore needed to support model-based projections of how climate change will affect ecosystem function. A variety of models have been developed to predict species or site-specific phenology of trees. However, extension of these models to other sites or species has proven difficult. Using meteorological and eddy covariance data for 29 forest sites (encompassing 173 site-years), we evaluated the accuracy with which 11 different models were able to simulate, as a function of air temperature and photoperiod, spatial and temporal variability in the onset of spring photosynthetic activity. In parallel, we also evaluated the accuracy with which dynamics in remotely sensed vegetation indices from MODIS captured the timing of spring onset. To do this, we used a subset of sites in the FLUXNET La Thuile database located in evergreen needleleaf and deciduous broadleaf forests with distinct active and dormant seasons and where temperature is the primary driver of seasonality. As part of this analysis we evaluated predictions from refined versions of the 11 original models that include parameterizations for geographic variation in both thermal and photoperiod constraints on phenology. Results from cross-validation analysis show that the refined models predict the onset of spring photosynthetic activity with significantly higher accuracy than the original models. Estimates for the timing of spring onset from MODIS were highly correlated with the onset of photosynthesis derived from flux measurements, but were biased late for needleleaf sites. Our results demonstrate that simple phenology models can be used to predict the timing of spring photosynthetic onset both across sites and across years at individual sites. By extension, these models provide an improved basis for predicting how the phenology and carbon budgets of temperature-limited forest ecosystems may change in the coming decades.
Coupled daily streamflow and water temperature modelling in large river basins
Vliet, M.T.H. van; Yearsley, J.R. ; Franssen, W.H.P. ; Ludwig, F. ; Haddeland, I. ; Kabat, P. - \ 2012
Hydrology and Earth System Sciences 16 (2012). - ISSN 1027-5606 - p. 4303 - 4321.
climate-change impact - new-brunswick - soil-temperature - catamaran brook - neural-networks - air-temperature - thermal regime - forest canopy - united-states - fraser-river
Realistic estimates of daily streamflow and water temperature are required for effective management of water resources (e.g. for electricity and drinking water production) and freshwater ecosystems. Although hydrological and process-based water temperature modelling approaches have been successfully applied to small catchments and short time periods, much less work has been done at large spatial and temporal scales. We present a physically based modelling framework for daily river discharge and water temperature simulations applicable to large river systems on a global scale. Model performance was tested globally at 1/2 × 1/2° spatial resolution and a daily time step for the period 1971–2000. We made specific evaluations on large river basins situated in different hydro-climatic zones and characterized by different anthropogenic impacts. Effects of anthropogenic heat discharges on simulated water temperatures were incorporated by using global gridded thermoelectric water use datasets and representing thermal discharges as point sources into the heat advection equation. This resulted in a significant increase in the quality of the water temperature simulations for thermally polluted basins (Rhine, Meuse, Danube and Mississippi). Due to large reservoirs in the Columbia which affect streamflow and thermal regimes, a reservoir routing model was used. This resulted in a significant improvement in the performance of the river discharge and water temperature modelling. Overall, realistic estimates were obtained at daily time step for both river discharge (median normalized BIAS = 0.3; normalized RMSE = 1.2; r = 0.76) and water temperature (median BIAS = -0.3 °C; RMSE = 2.8 °C; r = 0.91) for the entire validation period, with similar performance during warm, dry periods. Simulated water temperatures are sensitive to headwater temperature, depending on resolution and flow velocity. A high sensitivity of water temperature to river discharge (thermal capacity) was found during warm, dry conditions. The modelling approach has potential to be used for risk analyses and studying impacts of climate change and other anthropogenic effects (e.g. thermal pollution, dams and reservoir regulation) on large rivers.
Systematic errors in ground heat flux estimation and their correction
Gentine, P. ; Entekhabi, D. ; Heusinkveld, B.G. - \ 2012
Water Resources Research 48 (2012)9. - ISSN 0043-1397 - 15 p.
large-aperture scintillometer - apparent thermal-diffusivity - energy-balance closure - soil-temperature - net-radiation - land-surface - exchanges - forest
Incoming radiation forcing at the land surface is partitioned among the components of the surface energy balance in varying proportions depending on the time scale of the forcing. Based on a land-atmosphere analytic continuum model, a numerical land-surface model and field observations we show that high-frequency fluctuations in incoming radiation (with period less than 6 hours, for example due to intermittent clouds) are preferentially partitioned towards ground heat flux. These higher frequencies are concentrated in the 0-1 centimeter surface soil layer. Subsequently, measurements even at a few centimeters deep in the soil profile miss part of the surface soil heat flux signal. The attenuation of the high-frequency soil heat flux spectrum throughout the soil profile leads to systematic errors in both measurements and modeling, which require a very fine sampling near the soil surface (0-1 centimeter). Calorimetric measurement techniques introduce a systematic error in the form of artificial band-pass filter if the temperature probes are not placed at appropriate depths. In addition the temporal calculation of the change in the heat storage term of the calorimetric method can further distort the reconstruction of the surface soil heat flux signal. A correction methodology is introduced which provides practical application as well as insights into the estimation of surface soil heat flux and the closure of surface energy balance based on field measurements.
Climate-driven simulation of global crop sowing dates
Waha, K. ; Bussel, L.G.J. van; Müller, C. ; Bondeau, A. - \ 2012
Global Ecology and Biogeography 21 (2012)2. - ISSN 1466-822X - p. 247 - 259.
sown sugar-beet - s-and-h - soil-temperature - seedling emergence - tassel initiation - base temperature - high-resolution - spring wheat - corn growth - model
Aim To simulate the sowing dates of 11 major annual crops at the global scale at high spatial resolution, based on climatic conditions and crop-specific temperature requirements. Location Global. Methods Sowing dates under rainfed conditions are simulated deterministically based on a set of rules depending on crop-and climate-specific characteristics. We assume that farmers base their timing of sowing on experiences with past precipitation and temperature conditions, with the intra-annual variability being especially important. The start of the growing period is assumed to be dependent either on the onset of the wet season or on the exceeding of a crop-specific temperature threshold for emergence. To validate our methodology, a global data set of observed monthly growing periods (MIRCA2000) is used. Results We show simulated sowing dates for 11 major field crops world-wide and give rules for determining their sowing dates in a specific climatic region. For all simulated crops, except for rapeseed and cassava, in at least 50% of the grid cells and on at least 60% of the cultivated area, the difference between simulated and observed sowing dates is less than 1 month. Deviations of more than 5 months occur in regions characterized by multiple-cropping systems, in tropical regions which, despite seasonality, have favourable conditions throughout the year, and in countries with large climatic gradients. Main conclusions Sowing dates under rainfed conditions for various annual crops can be satisfactorily estimated from climatic conditions for large parts of the earth. Our methodology is globally applicable, and therefore suitable for simulating sowing dates as input for crop growth models applied at the global scale and taking climate change into account.
Methane emissions in two drained peat agro-ecosystems with high and low agricultural intensity
Schrier-Uijl, A.P. ; Kroon, P.S. ; Leffelaar, P.A. ; Huissteden, J.C. van; Berendse, F. ; Veenendaal, E.M. - \ 2010
Plant and Soil 329 (2010)1-2. - ISSN 0032-079X - p. 509 - 520.
broeikasgassen - methaan - emissie - veengronden - agro-ecosystemen - ontwaterde omstandigheden - landbouw - bodemtemperatuur - greenhouse gases - methane - emission - peat soils - agroecosystems - drained conditions - agriculture - soil temperature - nitrous-oxide fluxes - spatial variability - water-table - soil-temperature - ch4 - scale - n2o - grasslands - peatlands - cover
Methane (CH4) emissions were compared for an intensively and extensively managed agricultural area on peat soils in the Netherlands to evaluate the effect of reduced management on the CH4 balance. Chamber measurements (photoacoustic methods) for CH4 were performed for a period of three years in the contributing landscape elements in the research sites. Various factors influencing CH4 emissions were evaluated and temperature of water and soil was found to be the main driver in both sites. For upscaling of CH4 fluxes to landscape scale, regression models were used which were specific for each of the contributing landforms. Ditches and bordering edges were emission hotspots and emitted together between 60% and 70% of the total terrestrial CH4 emissions. Annual terrestrial CH4 fluxes were estimated to be 203 (±48%), 162 (±60%) and 146 (±60%) kg CH4 ha-1 and 157 (±63%), 180 (±54%) and 163 (±59%) kg CH4 ha-1 in the intensively managed site and extensively managed site, for 2006, 2007 and 2008 respectively. About 70% of the CH4 was emitted in the summer period. Farm based emissions caused per year an additional 257 kg CH4 ha-1 and 172 kg CH4 ha-1 for the intensively managed site and extensively managed site, respectively. To further evaluate the effect of agricultural activity on the CH4 balance, the annual CH4 fluxes of the two managed sites were also compared to the emissions of a natural peat site with no management and high ground water levels. By comparing the terrestrial and additional farm based emissions of the three sites, we finally concluded that transformation of intensively managed agricultural land to nature development will lead to an increase in terrestrial CH4 emission, but will not by definition lead to a significant increase in CH4 emission when farm based emissions are included