Laura Zavattaro

Indirect estimation of near-saturated hydraulic conductivity from readily available soil information

Application of process-based water flow and solute transport models is often hampered by insufficient knowledge of soil hydraulic properties. This is certainly true for dual- or multi-porosity models that account for non-equilibrium flow of water in macropores, where the saturated ‘matrix’ hydraulic conductivity is a particularly critical parameter. Direct measurement is possible, but this is impractical for larger scale studies (i.e. catchment or regional), where estimation methods (pedotransfer functions) are usually required. This paper presents pedotransfer functions for hydraulic conductivity at a pressure head of � 10 cm, K10, based on measurements of near-saturated hydraulic conductivity made with tension infiltrometers in 70 soil horizons at 37 different sites in

A survey on actual agricultural practices and their effects on the mineral nitrogen concentration of the soil solution

In intensive integrated crop-livestock farming systems, the surplus of N at the farm scale may be large and reflects on the N balance at the field scale. A study was conducted to assess the N fertilizer efficiency in four private farms in intensively cropped areas of NW Italy, and to monitor the effects of agricultural practices on the mineral N concentration of the soil solution, sampled every 2 weeks for 2 years and considered as an indicator of potential leaching. Two cultivation systems were compared in each farm, one involving continuous maize rotation, the other assuring a continuous soil cover (permanent meadow or winter cereal-maize double cropping system). The fertilization level in the arable crops was high (369‐509 kg N ha 1 year 1 ) compared to the crop removals, and resulted in a low efficiency, as indicated by the four examined efficiency indexes (calculated N surplus, N removal-fertilizer ratio, N apparent recovery, N use efficiency). The soil-water-nitrate concentration showed large temporal variations in the range of 1‐150 mg l 1 for five out of the eight cropping situations, while concentrations smaller than 10 mg l 1 were always recorded in the meadows and in one of the four soils (Aeric epiaquept). The fertilizer management that characterized each cropping system affected the soil-mineral-nitrate content in shallow arable soils. The longer soil cover duration in double-cropping systems did not result in a reduction of soil N compared to maize as a single crop, not even in winter (the bare-soil intercropping period in maize-based systems). However, the temporal oscillations of the concentration were buffered by the crop cover duration and by the presence of a shallow water table (1 m deep) in the soil profile. The average nitrate content of the soil could be predicted by the N uptake of the crop, the N removal‐fertilizer ratio, the soil pH and sand content, however no simple explanatory relationship was found with the experimental factors. Hence, in farm conditions, in the absence of sufficient data for a deterministic model approach, the target of reducing the risk of leaching should be achieved by maximizing the fertilizer efficiency.

Chemically and biologically-mediated fertilizing value of manure-derived biochar

This study evaluates the potential of manure-derived biochars in promoting plant growth and enhancing soil chemical and biological properties during a 150day pot experiment. Biochars from pyrolysis of poultry litter (PL) and swine manure (SM) at 400 and 600°C, and a commonly available wood chip (WC) biochar produced at high temperature (1000°C) were incorporated to silt-loam (SL) and sandy (SY) soils on a 2% dry soil weight basis. Ryegrass was sown and moisture was adjusted to 60% water filled pore space (WFPS). The PL400 and SM400 biochars significantly increased (p<0.05) shoot dry matter (DM) yields (SL soil) and enhanced nitrogen (N), phosphorus (P) and potassium (K) uptake by the plants in both soils, compared to the Control. All biochars significantly increased the soil carbon (C) contents compared to the Control. Total N contents were significantly greater for PL400 and PL600 treatments in both soils. The dehydrogenase activity (DA) significantly increased for PL400 and SM400 treatments and was positively correlated with the volatile matter (VM) contents of the biochars, while β-glucosidase activity (GA) decreased for the same treatments in both soils. All biochars significantly shifted (p≤0.05) the bacterial community structure compared to the Control. This study suggests that pyrolysis of animal manures can produce a biochar that acts as both soil amendment and an organic fertilizer as proven by increased NPK uptake, positive liming effect and high soil nutrient availability, while WC biochar could work only in combination with fertilizers (organic as well as mineral).

Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination

The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prepared powder and subsequent firing in the 800–1,000 °C range. These sensors were first tested in a laboratory apparatus under humid air and then in an homogenized soil and finally in field. The results evidenced that the screen printed film was able to give a response for a soil matric potential from about 570 kPa, that is to say well below the wilting point in the used soil.

Field Plots and Crop Yields Under Innovative Methods of Carbon Sequestration in Soil

This chapter reviews the issues related to the responses of crops and soil fertility to management strategies aimed to conserve soil carbon, especially for Mediterranean-Temperate conditions. It reports the main results from field experiments conducted in three different Italian sites in order to compare traditional and innovative soil treatments for carbon sequestration. Field agronomic treatments included traditional and minimum tillage, green manuring, two rates of mature compost application, and spreading of water-soluble Fe–porphyrin. Their effects were tested in different sites representing distinct pedo-climatic conditions.

Systematic variability enhances the reproducibility of an ecological study

Many scientific disciplines currently are experiencing a “reproducibility crisis” because numerous scientific findings cannot be repeated consistently1–4. A new but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduces reproducibility by amplifying impacts of lab-specific environmental factors not accounted for in study designs5–8. A corollary to this hypothesis is that the deliberate introduction of controlled systematic variability (CSV) in experimental designs can increase reproducibility. We tested this hypothesis using a multi-laboratory microcosm study in which the same ecological experiment was repeated in 14 laboratories. Each laboratory introduced environmental and genotypic CSV within and among treatments in replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). The introduction of genotypic CSV increased reproducibility of results in growth chambers but had no significant effect in glasshouses where reproducibility also was lower. Environmental CSV had little effect on reproducibility. This first deliberate attempt at reproducing an ecological experiment with added CSV reveals that introducing genotypic CSV in experiments carried out under controlled environmental conditions with stringent standardization can increase reproducibility by buffering against unaccounted lab-specific environmental and biotic factors that may otherwise strongly bias experimental outcomes.