Agriculture biologique | EPFL Graph Search

Lagriculture biologique est une méthode de production agricole qui vise à respecter les systèmes et cycles naturels, maintenir et améliorer l’état du sol, de l’eau et de l’air, la santé des végétaux et des animaux, ainsi que l’équilibre entre ceux-ci.vignette |Fruits et légumes cultivés en agriculture biologique. À cette fin, elle exclut le recours à la plupart des produits chimiques de synthèse, utilisés notamment par l'agriculture industrielle et intensive depuis le début du , les organismes génétiquement modifiés par transgénèse et la conservation des cultures par irradiation. La fertilisation du sol et la protection des plantes doivent donc être assurées en privilégiant au maximum l'utilisation d'engrais et de pesticides issus ou dérivés de substances naturelles ou la lutte biologique. Les pratiques d'agriculture biologique sont soumises à des normes contraignantes permettant la labellisation des produits et un prix de vente généralement plus élevé. Les motivations des agriculte

Comparative study of environmental impacts of imported organic products and regional conventional products – Geneva's case

Florence Escalera

Nowadays, the consumer is worried by his health and by the environmental protection. Two interesting groups, among the others, can be distinguished : persons worried of eating organic products and persons who consume regional products. What about imported organic products? And what about local conventional products? Which environmental impacts have they? The objective of the work was to compare products stemming from the organic farming and imported in Geneva with products stemming from the regional conventional agriculture, where the region is Geneva. Studied products are apple, tomato, wheat and egg. The origin of these organic products is New-Zealand, Netherland, Canada and United Kingdom, respectively. Results show that each production process involves specific impacts. A unique conclusion for all fruits, all vegetables, all cereals or all animal products is not possible. However, for the precise cases studied, we can say that for all products results show that the imported organic products lead more environmental impacts than regional conventional products. For tomato and egg, a production improvement could invert the tendency. For apple and wheat, a transport reduction will decrease environmental impacts. These results lead to some interrogations : Is Local agriculture enough to feed its inhabitants? Is conventional agriculture sustainable?

2009

Soil aggregation and associated nutrient content along a distance-from-tree gradient in a low input cropping system. Comparing the effect for two tree species: Mangifera indica (mango, Anacardiaceae) vs. Faidherbia albida (faidherbia, Fabaceae)

Pauline Chrobot

Trees can play a major role in improving soil quality and thus have the potential to enhance sustainability of agroecosystems. Although this has been well established, knowledge on the effect of individual trees on aggregate stability and associated-nutrient content remains scarce. This study aims to quantify the spatial extent and magnitude of influence of single-standing Mangifera indica (mango, Anacardiaceae) and Faidherbia albida (faidherbia, Fabaceae) trees on soil aggregate stability and aggregate-associated nutrient content (total carbon, nitrogen and phosphorus) in a lowinput maize cropping system. Mango and faidherbia differ fundamentally in their properties (e.g., phenology and N-fixing capacity) providing an interesting study system. We hypothesize that 1) the extent of tree influence on soil will be proportional to the tree crown, 2) soil aggregation and aggregate-associated nutrient content will decrease with distance from tree for both species due to greater organic matter inputs from leaves and roots closer to the tree, 3) the magnitude of tree influence will be greater for faidherbia relative to mango due to its N-fixing property. To test these hypotheses, soil samples, collected along four transects, laid out around each single tree and taken at four different distances (1, 4, 10 and 15 m) from the tree trunk, were fractionated and total carbon, nitrogen and phosphorus content within the different fractions was determined. Our results show that both species had an impact on soil fertility, but only the spatial influence of mango was proportional to its crown. We could identify no change in the measured indicators with distance around faidherbia suggesting the possibility that we were likely still in its impact zone. These results support the hypothesis that faidherbia has an extensive positive impact on the surrounding soil, and that mango crown also improves subcanopy soil fertility via a better aggregation and an increase in associated-nutrient content.

2017

Using PhenoCams to track crop phenology and explain the effects of different cropping systems on yield

Christoph Bachofen, Yujie Liu

CONTEXT: Crop phenology integrates information of how environmental drivers and management practices affect plant performance and crop yield. However, little is known about the impact of cropping systems (CS) on crop phenology and how this relates to differences in yield. OBJECTIVES: We assessed the applicability of PhenoCams to track crop phenology, how four CS, i.e., organic vs. conventional farming with either intensive or conservation (no/reduced) tillage affect the phenology of a pea-barley mixture and winter wheat, how crop phenology is related to harvest characteristics, e.g., grain yield and total N uptake, and explains CS effects on these characteristics. METHODS: We used time-lapse cameras (PhenoCams) to track vegetation changes in the two crops and extracted the green chromatic coordinate (GCC) to estimate different phenological metrics, i.e., dates with major changes in GCC (PhenoTimePoints), the duration between those (PhenoPhases), and the rate of increasing or decreasing GCC (PhenoSlopes). We assessed how phenological metrics were affected by different CS, and related pheno-logical metrics to harvest characteristics. RESULTS AND CONCLUSIONS: CS significantly affected phenological metrics of both crops, with less pronounced effects in the unfertilized pea-barley mixture compared to the fertilized winter wheat, and stronger effects for early-season than for late-season PhenoTimePoints. For winter wheat, organic compared to conventional farming caused an initial growth lag (up to 7 days) and a shorter duration (approximately 10 days) of the period of stable GCC. Winter wheat in reduced/no-tillage systems showed a tendency of delayed phenology (up to 5 days) compared to intensive tillage. While phenological metrics explained harvest characteristics of winter wheat well, they were almost unrelated to those of pea-barley, most likely because pea-barley yields were similar among CS. For winter wheat, effects of CS on harvest characteristics could be well explained by phenological metrics (max. R2 = 0.9). Thus, we demonstrated that delayed phenology acted as an important factor causing lower yield in organic compared to conventional farming. SIGNIFICANCE: PhenoCams are valuable tool for high-resolution temporal monitoring of crop phenology. As different CS have been proposed as a tool for climate change adaptation, we suggest that the effects of CS on crop phenology need to be considered as they may impact yield via changes in crop phenology, particularly in organic agriculture.

ELSEVIER SCI LTD2022

Using PhenoCams to track crop phenology and explain the effects of different cropping systems on yield

Christoph Bachofen, Yujie Liu

ELSEVIER SCI LTD2022

Pauline Chrobot

2017