DOI: 10.5281/zenodo.15163443
title: Dati sulla stabilità degli aggregati 2023

description: Introduction

Provide some background and key references that support the aim and scope of the individual pilot study. Introduce the problem and describe how the work will go beyond the state of the art to either support legume ecosystem services being valorised, develop our understanding of ecosystem services from legumes or how we improve the evaluation of legume ecosystem service provision.

Fertility management in Mediterranean agricultural systems, owning to their peculiar characteristics of climate and soils, is full of difficulties and complications. Firstly, those systems are characterized by low organic matter content in the soil, because of the contemporary presence in the soil of oxygen, high temperatures and humidity from April to October. Secondly, the winter period in the Mediterranean agricultural system is too cold for most crop growth, so the soil is often left bare. The winter period is normally the part of the year where the highest drainage occurs, due to low evaporation and, in many areas, high precipitations. The plant nutrients (mainly nitrates) available in the soil can therefore be leached downwards with the percolating water and eventually be lost from the subsequent crop root zone (Thorup-Kristensen et al., 2003).

The impact on yields is therefore very severe, especially when Mediterranean organic cropping systems are concerned (Bonciarelli et al., 2016), because the hypothesis of a crop system aimed at N self-sufficiency could be disregarded by the high complexity of N management (Fagnano and Bàrberi, 2007). The introduction of leguminous species in these cropping systems is therefore highly recommended, legumes could play an important role not just as grain crops, but also as fertility building crops (Thorup-Kristensen et al., 2012).

In recent past, across the world a general simplification of cropping systems and rotation has been happening. This has negative effects on a series of environmental and social impacts: higher reliance on chemical imputs such as fertilizer and pesticides (Mortensen and Smith, 2020; van der Werf et al., 2020), loss of biodiversity and reduction of nutrient cycling (Goglio et al., 2017; Tuomisto et al., 2012). Therefore a specific field trial has been set up in 1971 to assess rotation effects on crop performance at the Experimental Farm of the Department of Agricultural, Food and Environmental Sciences (Papiano, 42.96 N, 12.38 E, 163 m a.s.l.) on plain land under rainfed conditions. The experiment is still running at present. The aim of the experiment is comparing different rotation with continuous winter wheat (Triticum aestivum L.). The experimental design has been changed in several occasion since then. Since the beginning of the LegumES project, legume based rotations (Faba bean (Vicia faba var. minor L.)-winter wheat and chickpeas (Cicer arietinum L.)-what-field pea (Lathyrus sativus Lam.)-wheat) with two level of N fertilization for the wheat (0, 150 kg of N ha-1) (v-w 0, v-w 150,c-w-fp-w 0, c-w-fp-w 150)) will be assessed in comparison with continuous wheat (w150) with 150 kg of N ha-1 and a sunflower-wheat with a 150 kg of N ha-1 (s-w 150) which are common rotations in the area.

 

Objectives

The main objectives of this pilot study are to assess and showcase the overall rotational benefits of legumes in rainfed crop rotation located in the Mediterranean Climate. These objectives will allow to quantify the ES benefits due to the presence of faba bean, chickpeas and field pea in the rotation and compare the overall performance with the common rotation in the area (sunflower, wheat)

Specific objectives are:



Assess yield performance of the legume crop in the rotation

Assess yield performance of the cereal crop following the legume in the rotation

Assess the environmental impact of legumes in a cropping systems

Assess how N, P and K availability is affected by legumes

Assess the benefits of biological N fixation in the cropping systems

Assess how soil fertility is affected by legumes

Assess how aggregate stability is affected by the legumes in the rotation


 

Description of work

This pilot study is made of 4 main tasks. Tasks 12.2 are supported by ongoing funding sources. Tasks 12.2-12.5 are specifically supported by the LegumES project funding.

1)      Field trial data gathering

2)      Crop management of the field trial

3)      Biomass and yield monitoring

4)      Soil data monitoring

5)      Phenological observations

6)      Crop management observations

PS Task 12.1 Field data gathering

The rotation trial was established in 1974, however several changes have been made as time passed refocusing the objectives and the aims of the trial. The rotations which will be considered as part of the LegumES trial includes the continuous wheat with 150 kg ha-1of N, the sunflower-wheat rotation with 150 kg of ha-1 for the wheat, the faba bean-wheat rotation with a 150 kg N ha-1 for the wheat. Biomass and yield data, together with soil analysis data will be gathered and organised for the LegumES project.

PS Task 12.2 Crop management of the field trial

The crop management of the field trial will be carried on the basis of a protocol established as the various rotation have been established (Bonciarelli et al., 2016) and here briefly summarised. All the crops have been managed using both pesticides and mineral fertilizer as in conventional agriculture. For all rotations, all phases are simultaneously grown in each year, for a total of 66 plots (33 plots for each of 33 possible crop sequences by two residue management levels) in each of three blocks (198 plots in total), arranged according to a split-plot design, with crop residue management on the main plots and crop rotations/fertilisations on the subplots (24 m2 each). This crop management will be carried out also for the new rotation which will be established: Faba bean-wheat with 0 kg of ha-1 for wheat, chickpea-wheat-field pea-wheat with 150 kg N ha-1 for wheat and with 0 kg ha-1 of N for the wheat crop.

PS Task 12.3 Biomass and yield monitoring

Biomass and yield monitoring was carried out by collecting the mechanically harvested biomass and grain yield using a pilot scale combined harvester with the exception of summer crops (ie. Sunflower) where each plant was manually harvested (Bonciarelli et al., 2016). After measuring the weight of the residues and grain yield a sample of <200 g has been taken to measure the biomass and yield moisture. Moisture content of the biomass and yield was estimated as a difference between the dry and fresh weight of the sample which has been previously oven dried at 100°C for at least 48h. 

 

PS Task 12.4 Soil data analysis

For each of the plot (24 m2), two soil samples were randomly taken at different depths (0-15 cm, 15-30cm) which were then mixed to form a mixed sample of less than 500 of wet weight. The soil sampling will be carried out after harvest of all the crops present in the trial. For each mixed samples the following physical and chemical analysis will be carried out: Organic C with (Wikley-Black)(RI, 1999), .exchangeable P (Olsen Method), exchangeable K (Atomic absorption method), ammonium N (Spectrophotometric method with Nessler reactive), nitric N (Spectrophotometric method with Sodium salicylate), total N  Kieldahl method, cation exchange capacity (RI, 1999) and soil aggregate stability (Le Bissonnais, 2016). The soil sampling was accompanied with the bulk density method on the profile (0-30 cm) using the core method (Blake, 1965). At the beginning of the experiment, soil granulometry will be measured with the gravimetric method. 

PS Task 12.5 Phenological observations

Phenological observations will be carried with regards to the date of seeding, emergence, beginning of spiking/flowering, end of spiking/flowering, harvest for all the crops present in the key identified rotations (v-w 0, v-w 150,c-w-fp-w 0, c-w-fp-w 150, v-w 150, s-w150)).

PS Task 12.6 Crop management observations

For each plot, crop management will be recorded. This include date and type of tillage operations, fertilizer operations, pesticide treatments, seeding and harvest.  For the fertilizer operations, type and amount of fertilizer will be recorded together with pesticides (Bonciarelli et al., 2016).