Case Study Experiment - increasing organic matter with crops and conservation agriculture
The Italian researchers are testing the effectiveness of continuous soil cover and conservation agriculture practices to increase organic matter content. They are comparing untreated soil compared with cover crop and conservation agriculture management systems.
|Increasing organic matter content through long-term sustainable agriculture systems|
Chiara Pituello, Nicola Dal Ferro, Gianluca Simonetti, Antonio Berti, Francesco Morari (2015) Nano to macro pore structure changes induced by long-term residue management in three different soils. Ecosystems and Environment, Vol 217, 1 February 2016, Pages 49–58 doi:10.1016/j.agee.2015.10.029
Further information about the case study activities in Italian can be found here
The study area is located in the low Venetian plain (see right) and is characterized by sedimentary loamy soils with shallow groundwater (< 2 m). The local climate is sub-humid, with annual rainfall of about 850 mm. Temperatures increase from January (minimum average: 1.5 °C) to July (maximum average: 27.2 °C). Soil organic matter (SOM) content is strongly affected by the peculiar texture (low physical protection) and climatic conditions, and usually range from 10 to 20 g.kg-1 in the top layer. The altitude of the Veneto Region varies from ca. 3,300 m of the Dolomites Mountain to the sea level, from north to south. The low Venetian plain is generally flat and does not exceed 50 m a.s.l. (see below). The area surrounding the Venice lagoon (1,240 km2) is even lower, (2 m below the sea level) and currently cultivated due to land reclamation since 1st century BC.
Main soil threat
The main threat considered is the loss of SOM in mineral soils. It causes both GHG emissions and a worsening of soil functions (e.g. soil nutrient supply, hydraulic properties), pushing farmers to rely on external chemical input. In the last fifty years, SOM in northeast Italy decreased at rates ranging from 0.02 to 0.58 t C.ha-1.y-1 year as a consequence of the intensification and simplification of cropping systems (e.g. monoculture) and the uncoupling of crop and livestock production. Most recently, the removal of crop residue for bioenergy production raises further concern about its potential impact on SOM evolution.
Application of EU conditionality measures (i.e. mandatory crop rotations) has had only a marginal effect on SOM recovery, while other voluntary measures supported by the Regional Government (e.g. input of organic amendment, no-tillage) showed low acceptance by the farmers. Indeed, implementation of measures has been hindered by: a) technical, logistic and economic constraints (e.g. distance between amendment source and potential users); b) farmer's cultural diffidence; and c) uncertainties of their bio-physical effectiveness, due to a large variability in pedo-climatic conditions which strongly affect the interaction between organic input and carbon cycle.
Typical agricultural landscape in the low Venetian plain.
Other soil threats
The region also suffers loss of Used Agricultural Area (UAA) due to excessive urbanisation which affects mainly the fertile soils of the Venetian plain (Tempesta, 2008). In the last decades Veneto Region has undergone rapid industrial growth which has strongly sharpened competition for natural resources. It has been estimated that during 1970-2010, 15% of cultivated land in Veneto plain (c.a. 120,000 ha) was affected by soil sealing, decreasing the potential agricultural production and increasing the frequency of flood events. Intensive cultivation systems and Confined Animal Feeding Operations (CAFOs) also have a strong impact on the environment, causing problems such as nutrient leaching, GHGs emissions and loss of biodiversity.
Location and Digital Elevation Model (DEM) of the Veneto Region (Source: SRTM)
Geology & Soils
The composite geology of the Veneto region is the result of a series of geological events that took place in the course of thousands of years: the typical dolomitic conformation of the northern area was deposited on rhyolitic ignimbrites and andesitic, rhyolitic and dacite lava, which in turn were overlapped on the crystalline basement that was formed ca. 400 million years ago (Regione Veneto, 1990). The large number of faults indicates an intense tectonic activity and dislocation in the region that affected the subsidence and formation of the Venetian plain by causing the accumulation of alluvial and coastal deposits. The Venetian plain was formed in its southern part by the sedimentary action of Po River and in the northern one by the sedimentary action of Adige, Brenta, Piave and Tagliamento rivers. In particular, the low Venetian plain is characterised by sandy and silty-clay deposits due to the minimal slope of the land (down to 1‰) that sensibly reduces the transport capacity of the water courses. Accordingly, the soils of the low Venetian plain were formed by and evolved from the alluvial materials deposited over the millennia with the exception of the coastal area, where a consistent part of the soils is formed by sandy sediments of marine origin. According to the World Reference Base (Regione Veneto, 2005) the major soils of the low Venetian plain are Calcisols and Cambisols (below, left), characterised by low natural fertility due to low organic matter and carbon contents and low cation exchange capacity, while they contains excessive amounts of calcium carbonates (CaCO3). They are often characterized by shallow groundwater levels (< 2 m). The most relevant natural limitation of these soils is the lack of organic material that is strongly affected by the peculiar texture (low physical protection) and climatic conditions, and usually ranges from 10 to 20 g kg-1 in the top layer.
Soil groups and materials (WRB) (left) and Land Use in the Case Study (right) (Source: JRC).
Farming covers about 57% of the Veneto region territory, while the remaining area is occupied by woodlands (29%), urban areas (8%) and wetlands (6%). Agricultural areas are mainly concentrated in the Venetian plain (92%), comprising of cereals (maize, wheat), soybean, and horticulture cultivations (Table 14.1). Maize, representing ca. 80% of the total national production, allows Veneto to be the leading Italian region in the sector. Croplands are generally irrigated where the shallow water table does not contribute to groundwater irrigation.
Several phytogeographical, geomorphological, climatic and anthropogenic factors have contributed to the great heterogeneity of the Veneto landscapes. The Veneto region primarily includes the alpine (in the northern part) and continental biogeographic areas (in the central and southern part), although the vegetation was also sensitive to the geological substrate. The sedimentary substrates that dominate in the Venetian plain, allow the development of different ecosystems as they are characterized by limestones and dolomite rocks as well as marlstones. Nevertheless, the intense anthropogenic activity has deeply modified the landscape and the vegetation. The typical vegetation of the low Venetian plain used to include oak and hornbeam forests, predominantly dominated by Quercus robur and attributable to Asparago tenuifolii-Quercetum roboris. Now black locust (Robinia pseudoacacia L.) and poplar trees (e.g. Populus nigra L.) are more frequently met as a consequence of degraded areas and tree plantations standing between a complex system that mixes urban, agricultural and industrial areas. Close to the Venice lagoon, the influence of the sea and of lagoons and dune ridges favour the formation of a coastal area that includes typical plant communities such as Cakiletea maritimae, Ammophiletae and Quercion ilicis.
|Agricultural land use||Area %|
Main crops of the Venetian plain (ISTAT, 2010).
The continental climate of the low Venetian plain is sub-humid, with annual rainfall of about 850 mm. Temperatures increase from January (minimum average: 1.5 oC) to July (maximum average: 27.2 oC). The rainfall distribution (Figure 14.4) during the year is characterised by a maximum in June (ca. 100 mm) and minima in winter (50-60 mm per month from December to February). On average, relative humidity varies relatively little during the year, the maximum values being around 90% in winter and 75% in summer. The reference evapotranspiration (ET0) for the low Venetian plain is 945 mm in the median year, but can reach above 1,000 mm per year at a frequency of 20%. ET0 reaches a peak in July, when it is close to 160 mm (ca. 5 mm d-1) on average, exceeding rainfall in the period April-September. Rainfall deficit increases from June to September when it is close to 250 mm (Giardini, 2004).
Average annual (left) and mean monthly (right) precipitation and temperature of the low Venetian plain.
The Veneto region has a dense river network that includes some of the largest Italian rivers. In the south, the Po River flows through the plain and into the Adriatic Sea forming a large delta. The Adige River and its basin are just north of the Po River, expanding to about 12,000 km2, followed by the Brenta and Piave basins in the eastern part of the region. In the low Venetian plain, an unconfined shallow groundwater (ca. 1-3 m depth) is overlapped to confined aquifers (Provincia di Venezia e ARPAV, 2008). Shallow groundwater is located in sandy or silty layers, rarely on gravel layers.
Drivers and pressures
The main pressures on the soil resource concern the intensive agricultural practices that are particularly applied in the mineral soils of the low Venetian plain, in turn characterised by low natural SOM content. The simplification of cropping systems (e.g. monoculture) and the uncoupling of crop and livestock production have deteriorated the soil quality by reducing, for example, the external input of organic amendments.
The introduction of innovative and efficient agricultural technologies in arable lands has been hindered by the relatively small average size of farms in Veneto. Indeed more than 55% of the farms have an area smaller than 5 ha while only ca. 5% is larger than 30 ha. The sector is also strongly affected by fluctuating commodity prices, especially maize, that have led to a reduction of incomes and have forced farmers to rely on agricultural contractors. Mycotoxin contamination of maize kernels is another factor which has a strong influence on commodity price, especially in high intensive cultivation systems. Low farm incomes and inadequate generational turnover drove small farmers out of the market, especially in marginal areas (i.e. hilly and mountainous areas) where the phenomenon has been associated to land abandonment.
As observed in other European Countries, alternative use of the soil, such as for bioenergy crop production, conflicts with the traditional land use. It was estimated that in 2010 bioenergy crops were grown in more than 11,000 ha as follows: rapeseed (4,800 ha) and soybean (3,400 ha) for biodiesel and maize (1,700 ha) and sorghum (5,000 ha) for biogas (Regione Veneto, 2014). Most recently, the removal of crop residue for bioenergy production raises further concern about its potential impact on SOM evolution.
Status of soil threat
The most relevant limitation of the soils located in the low Venetian plain of the Veneto region is the lack of soil organic matter (SOM) that is strongly affected by their natural texture (low physical protection) and climatic conditions. Soil organic carbon (SOC), mainly stored in organic matter components, is generally lower in lowlands (1-2%) than in hilly and mountainous areas (2-5% or more) (below left). Moreover, SOC content is often less than 1% in Rovigo, Verona, Venezia and Padova districts (ARPAV, 2010), especially where intensive agriculture is practiced in the large scale and the input of organic material is poor or missing. In the last fifty years, SOM in northeast Italy decreased at rates ranging from 0.02 to 0.58 t C ha-1 y-1, enhancing the abovementioned natural low organic matter content of the low Venetian plain (below right).
Left: SOC content (%) in the Veneto region (ARPAV, 2010), Right: SOC change from 1962 to 2012. FYM: farmyard manure (Berti el al., 2015).
Effects of soil threat on soil functions
The following table ranks the effects of SOM decline on the soil functions in the Veneto.
|Functions of soil||Explanation||Effect|
|Food and other biomass production||Improvement of soil physical, chemical and biological properties, source of macronutrients||M|
|Environmental interaction: storage, filtering, buffering and transformation (including carbon pool)||soil C sink capacity, complexion of mineral cations, water retention, interaction with xenobiotics||H|
|Biological habitat and gene pool||SOM is the main source of energy for the decomposer organisms, hormone-like activities||H|
|Physical and cultural heritage|
|Platform for man-made structures: buildings, highways|
|Source of raw materials|
Effects of loss of soil organic matter on soil functions (H: High; M: Medium)
Maps on the current state of land use, soil degradation and soil conservation in the case study area have been produced using the WOCAT (World Overview of Conservation Approaches and Technologies) methodology
The steps of this process are as follows:
1) The area to be mapped is divided into distinctive land use systems (LUS).
2) The team gathers the necessary data on soil degradation and conservation for each LUS using a standardised questionnaire, in close consultation with local land users, and supported where possible by remote sensing or field data.
3) For each LUS, the soil degradation type, extent, degree, impact on ecosystem services, direct and indirect causes of degradation, as well as all soil conservation practices, are determined.
4) Once collected, the data is entered in the on-line WOCAT-QM Mapping Database from which various maps can be generated.
Following the principles of all WOCAT questionnaires, the collected data are largely qualitative, based on expert opinion and consultation of land users. This allows a rapid and broad spatial assessment of soil degradation and conservation/SLM, including information on the causes and impacts of degradation and soil conservation on ecosystem services.
More details about the methodology used to produce these maps and their interpretation can be found here.
Land Use (click on maps to expand)
The degree of degradation reflects the intensity of the degradation process, whilst the rate of degradation indicates the trend of degradation over a recent period of time (approximately 10 years).
The "effectiveness" of conservation is defined in terms of how much it reduces the degree of degradation, or how well it is preventing degradation. The Effectiveness trend indicates whether over time a technology has increased in effectiveness.
Administrative and socio-economic setting
From an economic point of view, the Veneto region is the third largest region in Italy for wealth production, contributing 9.4% of the national GDP (below right). In spite of the economic crisis, the Veneto region has one of the highest rates of employment in Italy (63.3% in 2013), while the unemployed were 7.6% of the workforce (see below). The Veneto region has a strong industrial vocation: the share of the wealth produced by the industry is 31.6%, although it decreased over the past 15 years, while the tertiary sector increased by of 66.5% from 2000 to 2012 (Regione Veneto, 2013). The agricultural sector (1.9% of GDP) is progressively integrated in the agri-food that develops a similar surplus value. The majority of CAFOs in the region is in the Venetian plain (77%), amounting about 1 million livestock units. CAFOs are particularly relevant in the northern part of the plain due to its abundance in water resources (ISTAT, 2010). Another important sector is fishing and aquaculture, representing the 9% of the national GDP. More than a third of the regional GDP comes from exports. In 2013, exports from the Veneto region were 13.5% of the national total, amounting to 52.6 billion €, and agriculture and agri-food sectors contributed 9% of the total. There are increasingly fewer agricultural enterprises and these are on average progressively becoming larger. The average utilised UAA has increased by over 40% just in the last ten years both in Veneto and in Italy, reaching 6.8 and 7.9 ha respectively, while the number of both Veneto and Italian companies has fallen by 32.4%. In 2010, the sole proprietor enterprises operated by landowners with exclusively owned land of small dimensions and heavily centred on the family of the farm manager were still the most widespread form; moreover, half of the Veneto farm managers are over 60 years old and other profit-making activities connected to farming are not widespread. The arrival of young people in the agriculture (more than 1,800 young farmers have started a farming activity during 2007-2013) is bringing a strong transformation component. The impulse for renewal is considerably large, although the farm managers under 40 years old represent just 7% of the Veneto enterprises (Regione Veneto, 2014).
Population in Veneto region (left) and GDP per capita trends for Italy and the Euro Area (right)
Employed dynamics in Veneto region and employed distinction for field of work
The Regional Government is the organism that can dictate the policies of improving the environmental quality. In the context of EU and national objectives and taking into account the local needs, strengths and weaknesses, the Veneto region government has defined strategies aiming to improve the local environment (Regione Veneto, 2007).
European agro-environmental directives have posed different restrictions to the farmers in order to mitigate their impact on water and soil resources. For instance, around 350,000 ha have been declared as Vulnerable Zones according to the Nitrate Directive, capping the organic nitrogen input and in turn the whole food productive chain. Within the last Rural Development Plan (2007-2013), expected results were defined in terms of area under successful land management contributing to ca. 132,000 ha for biodiversity and high nature value of farming and ca. 129,000 ha for water quality improvement. In this context, measures were introduced with the aim of enhancing water quality, protecting soils from degradation, safeguarding biodiversity, improving animal welfare, preserving and increasing agro-forestry area with high nature value and finally strengthening the effects of agro-forestry activities that reduce GHG emissions and improve air quality. In particular, during the period 2007-2013, the agro-environmental measures under the Rural Development Plan were supported by 79% of its programmed expenditure. Specific agro-environmental measures to enhance soil and environmental quality include: i) input of organic amendments; ii) application of conservation agriculture practices, such as no-tillage and the use of cover crops; iii) organic agriculture and iv) the creation of buffer strips. Application of good agricultural and environmental conditions (GAECs) under Cross Compliance (e.g. mandatory crop rotations) has had only a marginal effect on SOM recovery, while the voluntary Regional Government ones (e.g. input of organic amendment, no-tillage etc.) showed low acceptance by the farmers. Indeed, implementation of measures has been hindered by: i) technical, logistic and economic constraints (e.g. distance between amendment source and potential users); ii) farmer’s cultural diffirence; iii) uncertainties of their bio-physical effectiveness, due to a large variability in pedo-climatic conditions which strongly affect the interaction between organic input and C cycle. Measures financed by the Regional Government are still valid short term practices to enhance soil quality.
Low acceptance of the voluntary Regional Government measures clearly demonstrates the low awareness of the farmers for the soil threat. A rethinking of the present agriculture productive models should be considered in order to suggest alternative models aiming to increase the efficiency of the farm in terms of nutrient and carbon cycles and energy use. Farmer education, dissemination and participation are also necessary to identify the potential risk associated with the SOM loss and implement viable alternatives.
Biochar application has been also suggested as a measure to increase stable SOC content.
The relevant end users and stakeholders include;
- Agro-Environmental Bureau, Regional Government, Regione Veneto,
- Veneto Agricoltura, Regional agricultural extension service, Regione Veneto,
- Confagricoltura Veneto, regional farmer association,
- Coldiretti Veneto, regional farmer association,
- Confederazione Italiana Agricoltura Padova, regional farmer association.
In the first phase of the project, a stakeholder platform will be established with farmer associations, extension service and policymakers. Preliminary meetings will be organized to identify optimal strategies to restore soil functions. The results obtained in the study sites and potential constraints will be analyzed in periodical meetings and field days organized in cooperation with other WPs. A dedicated web platform will be built to share information among stakeholders with a blog to discuss demonstration and monitoring relevancies and to have a continuous feedback.
The first workshop in Veneto had 16 participants of whom two were women (+4 University staff members). They were from the regional government and the agricultural private sector. Men were landowners, land managers, private sector advisors to public enterprises and providers of information. In the second workshop with 13 participants still two women attended (+4 University staff members), neither was a landowner but both were involved in the decisions about the land use. Both women said their role would not change with a change in land use. In the evaluation, it was generally ignored that there are typical roles for men and women in the region. It was mentioned in the questionnaire that men are more pragmatic and women more sensitive to changes. All participants admitted that they want to change the land use to improve the soil and that they would invest in more sustainable land management.
ARPAV, Agenzia Regionale per la Prevenzione e Protezione Ambientale del Veneto, 2010. Mappa CO – anno 2010. http://www.arpa.veneto.it/ (26/09/2014).
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ISTAT, Istituto Nazionale di statistica, 2010. 6° Censimento generale dell’agricoltura 2010. Caratteristiche strutturali delle aziende agricole. Dipartimento per i censimenti e gli archivi amministrativi e statistici, Roma.
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Regione Veneto, 2007. Programma di sviluppo rurale per il veneto 2007-2013. Dipartimento Agricoltura e Sviluppo Rurale, Venezia.
Regione Veneto, 2013. Statistical Report 2013 - Transformation and development. http://www.regione.veneto.it/web/statistica (26/09/2014).
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Tempesta T., 2008. Consumo di suolo o consumo di ambiente? Rivista di Economia Agraria 4,453-468.