Carlo Grignani

Developing a regional agronomic information system for estimating nutrient balances at a larger scale

Abstract The determination of nutrient surplus (fertiliser-offtake) is one of the indicators of potential losses from the agricultural system to the environment and can be applied at different geographical scales, from field to regional. When information is collected from individual farmers, the sample size is usually small as compared to the total number of the farms in a particular area. Official databases, when present, are more objective and contain information on all the farms in the area and as such provide information regarding the variability that exists between farms of a region. A geographical information system was built using all the information available in official databases to estimate soil surface nutrient balances at a regional scale within a 7773 ha area in Northwest Italy, where agriculture is very intensive. The nutrient surplus was calculated for the main farm types. Dairy farms showed the greatest surplus for all nutrients considered with values greater than 320 kg ha −1 for N and K and 110 kg ha −1 for P. Pig livestock farms followed next, with excesses greater than 270 kg N ha −1 , 100 kg P ha −1 and 220 kg K ha −1 . Cattle livestock farms showed the lowest surplus, compared to the other livestock farms, with values close to 190 kg N ha −1 , 80 kg P ha −1 and 230 kg K ha −1 . Farms without livestock showed the closest equilibrium between fertilisation and offtake, with a surplus in N, P and K equal to 40, 20 and 70 kg ha −1 , respectively. Despite the fact that local legislation only regulates slurry management precisely, it appeared that larger surpluses could be associated to the use of solid manure. Scenario analyses showed that manure exchange between farms in the area could lead to a drastic reduction in the use of mineral fertilisers, but at the regional scale an acceptable surplus can only be attained for N and K, while the excess of P remains a serious problem for the environment. The study indicated where the lack of information appears to be more critical and suggested options for a more accurate and organised acquisition of data. The results can be used for further studies, for instance with the aim of estimating the fate of nutrient surplus in the soil or in the air using simulation models.

Greenhouse gas emissions and soil properties following amendment with manure-derived biochars: Influence of pyrolysis temperature and feedstock type.

Manure-derived biochars can offer a potential option for the stabilization of manure, while mitigating climate change through carbon sequestration and the attenuation of nitrous oxide emission. A laboratory incubation study was conducted to assess the effects of four different manure-derived biochars produced from different feedstocks (poultry litter and swine manure) at different temperatures (400 or 600xa0°C). A commonly available standard wood chip biochar, produced at a greater temperature (1000xa0°C), and non-amended treatments were used as references. Two different soils (sandy and silt-loam) were amended with 2% (w/w) biochar on a dry soil weight basis (corresponding to 20xa0Mgxa0ha(-1)), with the soil moisture being adjusted to 75% saturation level. After a pre-incubation period (21 days), 170xa0kgxa0Nxa0ha(-1) of NH4NO3 fertilizer was added. Measurements of CO2, N2O, CH4 emissions and soil N mineralisation were carried out on different days during the 85 days of incubation. The net C mineralization and N2O emissions from both soils amended with poultry litter biochar at 400xa0°C were significantly greater than the other biochar treatments. Nitrate availability was greater in both soils in which the manure-derived biochar was used instead of the standard biochar. All of the biochars increased the pH of the silt-loam, sub-acid soil, but failed to improve the cation exchange capacities (CEC) in either soil. Total C and N, P, K and Mg (except Ca) were significantly increased in the manure-derived biochar amended soils, compared to the Control, and were positively correlated to the biochar nutrient contents. This study indicates that the soil application of biochar engenders effects that can vary considerably according to the biochar properties, as determined on the basis of the feedstock types and process conditions. Low-temperature biochar production from manure represents a possible way of producing a soil amendment that can stabilize C while supplying a significant quantity of nutrients.

Field measurement of net nitrogen mineralization of manured soil cropped to maize.

We evaluated the in situ net nitrogen (N) mineralization in a soil cropped to maize and fertilized for 11xa0years with cattle slurry or farmyard manure, both common on livestock farms of the Po River valley in Northern Italy. The net N mineralization of the tilled soil layer was measured in six consecutive incubation periods after manure application, for a total of 12xa0weeks, using the polyethylene buried bags technique. Results showed that net N mineralization was followed by N immobilization and finally, by mineralization whose rate increase until maize flowering. On average, net N mineralization was 70.4xa0kgxa0N ha−1, with the majority being released during the last measurement period. The time and extent of net N mineralization and plant N uptakes were not affected by fresh manure application. Instead, the effect of past management increased the maximum net N mineralization rate obtained with farmyard manure. The buried bag technique probably underestimates the total amount of mineralized N available for crop growth because it excludes the presence of the plant.

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).

Assessing agro-environmental performance of dairy farms in northwest Italy based on aggregated results from indicators.

Dairy farms control an important share of the agricultural area of Northern Italy. Zero grazing, large maize-cropped areas, high stocking densities, and high milk production make them intensive and prone to impact the environment. Currently, few published studies have proposed indicator sets able to describe the entire dairy farm system and their internal components. This work had four aims: i) to propose a list of agro-environmental indicators to assess dairy farms; ii) to understand which indicators classify farms best; iii) to evaluate the dairy farms based on the proposed indicator list; iv) to link farmer decisions to the consequent environmental pressures. Forty agro-environmental indicators selected for this study are described. Northern Italy dairy systems were analysed considering both farmer decision indicators (farm management) and the resulting pressure indicators that demonstrate environmental stress on the entire farming system, and its components: cropping system, livestock system, and milk production. The correlations among single indicators identified redundant indicators. Principal Components Analysis distinguished which indicators provided meaningful information about each pressure indicator group. Analysis of the communalities and the correlations among indicators identified those that best represented farm variability: Farm Gate N Balance, Greenhouse Gas Emission, and Net Energy of the farm system; Net Energy and Gross P Balance of the cropping system component; Energy Use Efficiency and Purchased Feed N Input of the livestock system component; N Eco-Efficiency of the milk production component. Farm evaluation, based on the complete list of selected indicators demonstrated organic farming resulted in uniformly high values, while farms with low milk-producing herds resulted in uniformly low values. Yet on other farms, the environmental quality varied greatly when different groups of pressure indicators were considered, which highlighted the importance of expanding environmental analysis to effects within the farm. Statistical analysis demonstrated positive correlations between all farmer decision and pressure group indicators. Consumption of mineral fertiliser and pesticide negatively influenced the cropping system. Furthermore, stocking rate was found to correlate positively with the milk production component and negatively with the farm system. This study provides baseline references for ex ante policy evaluation, and monitoring tools for analysis both in itinere and ex post environment policy implementation.

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.

Changes in soil mineral N content and abundances of bacterial communities involved in N reactions under laboratory conditions as predictors of soil N availability to maize under field conditions

Proper management of soil fertility requires specific tools for predicting N availability for crops as a consequence of different fertilization strategies. More information is required, especially for organic fertilizers, depending on their mineralization rate, composition, and processing (i.e., fresh or composted manure), as well as their effects on soil properties. Laboratory soil incubations were used as a proxy for understanding plant–soil N dynamics under field conditions. Chemical and microbiological measurements as contents of mineral N, potentially mineralizable N and the abundance of key genes regulating the overall N cycle were used as predictors of mineral N availability to maize in two contrasting pedoclimatic conditions. Our results showed that there was a good correlation between chemical and microbiological measurements from laboratory soil incubation experiments and soil–plant N dynamics of maize cropping systems. Mineralization patterns from soil incubation proved to be useful for optimizing fertilization management of maize under field conditions as long as incubation time is normalized over maize growth cycle, according to the simplified model of growth degree days. Average cumulative soil mineral N values calculated over a short incubation period (42xa0days) showed a significant correlation (R2u2009=u20090.72, pu2009<u20090.05) with maize N uptake. The shape and kinetic parameters of net N mineralization from medium-term (112xa0days) soil incubation provided consistent information on the interaction between fertilizers and native fertility. The abundance of N fixation, nitrification, and denitrification genes (nifH, amoA, nirK, and nirS) was sensitive to soil characteristics and N fertilization. This work provides a suitable starting point for developing a crop-based approach for using incubation data to optimize maize fertilization. However, more studies with different maize cultivars and pedoclimatic conditions are needed to generalize this approach.

Genotypic variability enhances the reproducibility of an ecological study

Many scientific disciplines are currently experiencing a reproducibility crisis because numerous scientific findings cannot be repeated consistently. A novel but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduce reproducibility by amplifying the impacts of laboratory-specific environmental factors not accounted for in study designs. A corollary to this hypothesis is that a deliberate introduction of controlled systematic variability (CSV) in experimental designs may lead to increased reproducibility. To test this hypothesis, we had 14 European laboratories run a simple microcosm experiment using grass (Brachypodium distachyon L.) monocultures and grass and legume (Medicago truncatula Gaertn.) mixtures. Each laboratory introduced environmental and genotypic CSV within and among 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 led to 18% lower among-laboratory variability in growth chambers, indicating increased reproducibility, but had no significant effect in glasshouses where reproducibility was generally lower. Environmental CSV had little effect on reproducibility. Although there are multiple causes for the reproducibility crisis, deliberately including genetic variability may be a simple solution for increasing the reproducibility of ecological studies performed under stringently controlled environmental conditions.A microcosm experiment replicated across 14 laboratories shows that deliberate inclusion of genetic variation enhances the reproducibility of an ecological study.

Towards the co-ordination of terrestrial ecosystem protocols across European research infrastructures

Abstract The study of ecosystem processes over multiple scales of space and time is often best achieved using comparable data from multiple sites. Yet, long‐term ecological observatories have often developed their own data collection protocols. Here, we address this problem by proposing a set of ecological protocols suitable for widespread adoption by the ecological community. Scientists from the European ecological research community prioritized terrestrial ecosystem parameters that could benefit from a more consistent approach to data collection within the resources available at most long‐term ecological observatories. Parameters for which standard methods are in widespread use, or for which methods are evolving rapidly, were not selected. Protocols were developed by domain experts, building on existing methods where possible, and refined through a process of field testing and training. They address above‐ground plant biomass; decomposition; land use and management; leaf area index; soil mesofaunal diversity; soil C and N stocks, and greenhouse gas emissions from soils. These complement existing methods to provide a complete assessment of ecological integrity. These protocols offer integrated approaches to ecological data collection that are low cost and are starting to be used across the European Long Term Ecological Research community.

Comparison of ammonia emissions from animal wastes and chemical fertilizers after application in the soil

BackgroundApplication of different chemical fertilizers and manures is a major source of ammonia (NH3) emission. The rate and total amount of NH3 emission are related to different parameters such as climatic conditions, soil characteristics and kind of fertilizer. The current study has indicated the NH3 emission from bovine slurry, pig slurry and ammonium nitrate fertilizer after application on two soils. Two different methods were used to measure NH3 emissions: the method that use acid traps and the method that use photoacoustic infrared gas analyzer.ResultsIn both soils the rate of NH3 emission was the greatest from the denser bovine slurry, declined in the pig slurry followed by the ammonium nitrate treatment and the control. The rate of soil infiltration could be the main factor that explained these differences. For all treatments the amount of total NH3 losses reduced in the more acidic soil. For all fertilizers the highest NH3 fluxes were measured in the first hours after spreading. A good agreement observed between the two methods is used for determining of NH3 emission. The use of a multi-gas monitor (MGM) is simple and accurate and produces a continuous series of NH3 concentration in time.ConclusionThe rate and amount of NH3 emission was related to the kind of fertilizers and interaction of these treatments with soils. The results of current study confirmed that comparison of chemical fertilizers and slurry for NH3 emission is difficult because the reaction of these two groups of fertilizer is totally different.