Maurizio Borin

Ecological interpretation of weed flora dynamics under different tillage systems

In northern Italy, on soil managed with three different tillage systems (conventional tillage, ridge tillage, and no-tillage) and submitted to standard cultural practices (crop rotation, and chemical weed control), the weed vegetation was assessed at the beginning of the trial (1987) and after six, and eight years. The aims were to evaluate (1) the effect of tillage systems on the weeds; and (2) the possibility of linking the floristic changes under reduced disturbance to the theory of ecological succession. The weeds were categorised according to life-forms (biological groups), periodicity types (ecophysiological groups), dispersal types and seed longevity. Data were analysed using Sorensons Indices of Similarity, the Independence test, and Principal Components Analysis. The tillage systems profoundly altered the weed community: in undisturbed soils the importance of the geophyte and hemicryptophyte species, and among the annuals, Digitaria sanguinalis, Conyza canadensis and Kickxia elatine increased, as well as that of the wind-dispersed weeds. The species linked to disturbance were annuals and in particular Amaranthus spp., Chenopodium album and Echinochloa crus-galli. After eight years the floristic evolution in the reduced tillage system can be interpreted on the basis of ecological succession. The community that has formed assumes, from the quantitative point of view, characteristics of a pioneer community of secondary succession with a predominance of annual species and a large number of wind-dispersed plants. Qualitatively there is a movement towards a more mature community that could become similar to that of the woodland edge, with more perennial species, shrubs, and bird-dispersed plants. The implications of these conclusions are discussed in terms of weed management.

Effects of tillage systems on energy and carbon balance in north-eastern Italy

An energy analysis of three cropping systems with different intensities of soil tillage (conventional tillage, CT; ridge tillage, RT; no tillage, NT) was done in a loamy-silt soil (fulvi-calcaric Cambisol) at Legnaro, NE Italy (45°21′N, 11°58′E, 8 m above sea-level (a.s.l.), average rainfall 822 mm, average temperature 11.7°C). This and measurements of the evolution of the organic matter content in the soil also allowed the consequences to be evaluated in terms of CO2 emissions. The weighted average energy input per hectare was directly proportional to tillage intensity (CT > RT > NT). Compared with CT, total energy savings per hectare were 10% with RT and 32% with NT. Average energy costs per unit production were fairly similar (between 4.5 and 5 MJ kg−1), with differences of 11%. The energy outputs per unit area were highest in CT for all crops, and lowest in NT. The RT outputs were on average more similar to CT (−12%). The output/input ratio tended to increase when soil tillage operations were reduced, and was 4.09, 4.18 and 4.57 for CT, RT and NT, respectively. As a consequence of fewer mechanical operations and a greater working capacity of the machines, there was lower fuel consumption and a consistently higher organic matter content in the soil with the conservation tillage methods. These two effects result in less CO2 emission into the atmosphere (at 0°C and pressure of 101.3–103 kPa) with respect to CT, of 1190 m3 ha−1 year−1 in RT and 1553 m3 ha−1 year−1 in NT. However, the effect owing to carbon sequestration as organic matter will decline to zero over a period of years.

Abatement of NO3–N concentration in agricultural waters by narrow buffer strips

The performance of narrow buffer strips in abating the NO3-N concentrations in the water coming from cropland was tested in an experiment carried out on the low plains of the Veneto Region (northeast Italy). The buffer was composed of a 5-m wide grass strip and a 1-m wide row of trees. Maize and wheat were cultivated in the neighbouring field during the monitoring period (December 1997-June 1999). Four experimental conditions were monitored, deriving from a combination of two levels of crop N fertilisation and two sizes of buffer trees. The narrow buffer was very effective in abating NO3-N concentrations, allowing water to be discharged with a concentration always below 2 ppm. Its zone of influence might be bigger than its simple width. The abatement was also efficient during winter. Tree size showed no evident effect on the reduction of the concentration.

Effects of poultry manure and mineral fertilizers on the quality of crops

Poultry manure and mineral fertilizers at two rates of application (medium and high) and in different combinations, together with a non-fertilized control, were tested at the Experimental Station of the Agricultural University of Padova, Italy (45° 21′ N, 11° 58′ E) in 1985–89. Compared to the control, all the fertilization treatments increased the incidence of larger-sized bulbs of onion and tubers of potato, improved the fruit colour of processing tomato and the raw protein content of spinach, but reduced the acidity and acids: soluble solids ratio of tomato and the dry matter content of spinach leaves. In addition, the application of 140 kg/ha of N, 140 kg/ha of P 2 O 5 and 100 kg/ha of K 2 O as mineral fertilizer or as poultry manure gave the best scores of processing suitability of potato, both for sticks and chips. All the fertilization formulae, except for 140 kg/ha of N, 140 kg/ha of P 2 O 5 and 100 kg/ha of K 2 O as poultry manure alone, showed significant decreases in the extractable sucrose ratio in sugarbeet, compared with the control. In processing tomato, the best scores of suitability for paste transformation were obtained with mixed fertilization (1/3 poultry manure and 2/3 mineral fertilizers) applying 210 kg/ha of N, 210 kg/ha of P 2 O 5 and 150 kg/ha of K 2 O and the plots receiving only mineral fertilizers produced fruits with less favourable values of pH and electrical conductivity compared to the poultry manured ones.

Performance of two small subsurface flow constructed wetlands treating domestic wastewaters in Italy

The performance of a vertical and a horizontal subsurface flow wetland (v-SSF and h-SSF), designed for treating domestic wastewater from a single family, was investigated by monitoring total nitrogen (TN), nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), total phosphorus (TP), chemical oxygen demand (COD) and the dissolved oxygen (DO) content of the influent and the effluent wastewater of each system during the first two years of operation. The growth of Phragmites australis in each system was recorded by measuring the height and observing their general conditions. The treated domestic wastewater presented similar chemical–physical characteristics in the two systems which operated in analogous environmental conditions. The median influent characteristics were: TN 81.9 mg L−1, NO3-N 0.19 mg L−1, NH4-N 33.5 mg L−1, TP 11.9 mg L−1 and COD 354.5 mg L−1. During the whole monitoring period median reductions in the v-SSF were TN 71%, NH4-N 94%, TP 27% and COD 92% whereas in the h-SSF they were TN 59%, NH4-N 21%, TP 52% and COD 70%. Internal production of NO3-N was observed, mainly in the v-SSF probably due to the difference in oxygen availability in the medium and the design of the system. DO concentration increased in the effluents in both years, with higher values measured in v-SSF than in h-SSF. The reduction performance increased in the second year, particularly in v-SSF, whereas no statistical differences were observed between spring–summer and autumn–winter periods. P. australis reached maximum development at the end of summer in both systems and maintained a stable height during autumn–winter. In h-SSF the vegetation located close to the influent showed lower growth than in the rest of the bed.

Effects of four cultivation systems for maize on nitrogen leaching 1. Field experiment

Abstract An experiment was conducted for 3 years on the Venetian Plain (northeast Italy) to evaluate the environmental impact of four cropping systems at different input levels. The four systems were: (A) higher inputs with pesticides, chemical fertilizers and liquid manure; (B) higher inputs with pesticides and chemical fertilizers; (C) lower inputs with low doses of fertilizers, post-emergence herbicides and use of cover crops; (D) organic, with low inputs without artificial fertilizers or pesticides. To assess the environmental impact samples of groundwater, soil and crop were taken from one field in each system, cultivated with maize but subjected to various management strategies. The results showed large differences in the nitrate nitrogen (NO 3 -N) concentration in the shallow groundwater, ranging from a mean value of 7.89mgl −1 in system A to 2.21 mg l −1 in system C. Less variability was observed for total Kjeldhal nitrogen (TKN): a maximum of 5.69 mg l −1 for system D and a minimum of 2.74mg l −1 for system B. Total annual nitrogen losses (TKN + N-NO 3 ) were 48, 19, 16 and 15 kg ha −1 year −1 in the four cultivation systems, respectively.

Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley.

In intensive agricultural systems runoff is one of the major potential diffuse pollution pathways for pesticides and poses a risk to surface water. Ditches are common in the Po Valley and can potentially provide runoff mitigation for the protection of watercourses. The effectiveness depends on ditch characteristics, so there is an urgent need for site-specific field trials. The use of a fugacity model (multimedia model) can allows recognition of the mitigation main processes. A field experiment was conducted in order to evaluate the mitigation capacity of a typical vegetated ditch, and results were compared with predictions by a fugacity model. To evaluate herbicide mitigation after an extreme runoff, the ditch was flooded with water containing mesotrione, S-metolachlor and terbuthylazine. Two other subsequent floods with uncontaminated water were applied 27 and 82 days later to evaluate herbicides release. Results show that the ditch can immediately reduce runoff concentration of herbicides by at least 50% even in extreme flooding conditions. The half-distances were about 250 m. As a general rule, a runoff of 1 mm from 5 ha is mitigated by 99% in 100 m of vegetated ditch. Herbicides retention in the vegetated ditch was reversible, and the second flood mobilized 0.03-0.2% of the previous one, with a concentration below the drinking water limit of 0.1 μg L-1. No herbicide was detected in the third flood, because the residual amount in the ditch was too low. Fugacity model results show that specific physical-chemical parameters may be used and a specific soil-sediment-plant compartment included for modelling herbicides behaviour in a vegetated ditch, and confirm that accumulation is low or negligible for herbicides with a half-life of 40 days or less. Shallow vegetated ditches can thus be included in a general agri-environment scheme for the mitigation of pesticides runoff together with wetlands and linear buffer strips. These structures are present in the landscape, and their environmental role can be exploited by proper management.

Simulation of herbicide contamination of the aquifer North of Vicenza (North-East Italy)

Abstract The contamination of the aquifer north of Vicenza (North-East Italy) by atrazine, simazine and alachlor has been simulated developing a simple model based on the fugacity model. The simulation has been carried out taking into account the period 1964–1990 and the results have been compared with the analytical data of the period 1987–1990. The median concentration (C50) of atrazine measured in the aquifer was 0.028, 0.044 and 0.015 μg/l in 1987, 1988 and 1989–1990 respectively. The simulated values showed a satisfactory behaviour of the model concerning the order of magnitude of the phenomenon. Similar results have been obtained for simazine and alachlor.

Chromium in Agricultural Soils and Crops: A Review

The mobility and distribution of metals in the environment is related not only to their concentration but also to their availability in the environment. Most chromium (Cr) exists in oxidation states ranging from 0 to VI in soils but the most stable and common forms are Cr(0), Cr(III), and Cr(VI) species. Chromium can have positive and negative effects on health, according to the dose, exposure time, and its oxidation state. The last is highly soluble; mobile; and toxic to humans, animals, and plants. On the contrary, Cr(III) has relatively low toxicity and mobility and it is one of the micronutrients needed by humans. In addition, Cr(III) can be absorbed on the surface of clay minerals in precipitates or complexes. Thus, the approaches converting Cr(VI) to Cr(III) in soils and waters have received considerable attention. The Cr(III) compounds are sparingly soluble in water and may be found in water bodies as soluble Cr(III) complexes, while the Cr(VI) compounds are readily soluble in water. Chromium is absorbed by plants through carriers of essential ions such as sulfate. Chromium uptake, accumulation, and translocation, depend on its speciation. Chromium shortage can cause cardiac problems, metabolic dysfunctions, and diabetes. Symptoms of Cr toxicity in plants comprise decrease of germination, reduction of growth, inhibition of enzymatic activities, impairment of photosynthesis and oxidative imbalances. This review provides an overview of the chemical characteristics of Cr, its behavior in the environment, the relationships with plants and aspects of the use of fertilizers.

Assessment of energy potential from wetland plants along the minor channel network on an agricultural floodplain

Renewable energy sources such as biomasses can play a pivotal role to ensure security of energy supply and reduce greenhouse gases through the substitution of fossil fuels. At present, bioenergy is mainly derived from cultivated crops that mirror the environmental impacts from the intensification of agricultural systems for food production. Instead, biomass from perennial herbaceous species growing in wetland ecosystems and marginal lands has recently aroused interest as bioenergy for electricity and heat, methane and 2nd-generation bioethanol. The aim of this paper is to assess, at local scale, the energy potential of wetland vegetation growing along the minor hydrographic network of a reclamation area in Northeast Italy, by performing energy scenarios for combustion, methane and 2nd-generation ethanol. The research is based on a cross-methodology that combines survey analyses in the field with a GIS-based approach: the former consists of direct measurements and biomass sampling, the latter of spatial analyses and scaling up simulations at the minor channel network level. Results highlight that biomass from riparian zones could represent a significant source of bioenergy for combustion transformation, turning the disposal problem to cut and store in situ wetland vegetation into an opportunity to produce sustainable renewable energy at local scale.