Eric Blanchart

Fourteen years of evidence for positive effects of conservation agriculture and organic farming on soil life

Conventional agriculture strongly alters soil quality due to industrial practices that often have negative effects on soil life. Alternative systems such as conservation agriculture and organic farming could restore better conditions for soil organisms. Improving soil life should in turn improve soil quality and farming sustainability. Here, we have compared for the first time the long-term effects of conservation agriculture, organic farming, and conventional agriculture on major soil organisms such as microbes, nematofauna, and macrofauna. We have also analyzed functional groups. Soils were sampled at the 14-year-old experimental site of La Cage, near Versailles, France. The microbial community was analyzed using molecular biology techniques. Nematofauna and macrofauna were analyzed and classified into functional groups. Our results show that both conservation and organic systems increased the abundance and biomass of all soil organisms, except predaceous nematodes. For example, macrofauna increased from 100 to 2,500xa0%, nematodes from 100 to 700xa0%, and microorganisms from 30 to 70xa0%. Conservation agriculture showed a higher overall improvement than organic farming. Conservation agriculture increased the number of many organisms such as bacteria, fungi, anecic earthworms, and phytophagous and rhizophagous arthropods. Organic farming improved mainly the bacterial pathway of the soil food web and endogeic and anecic earthworms. Overall, our study shows that long-term, no-tillage, and cover crops are better for soil biota than periodic legume green manures, pesticides, and mineral fertilizers.

Effects of organic and inorganic fertilization on soil bacterial and fungal microbial diversity in the Kabete long-term trial, Kenya

The effects of crop manure and inorganic fertilizers on composition of microbial communities of central high land soils of Kenya are poorly known. For this reason, we have carried out a thirty-two-year-old long-term trial in Kabete, Kenya. These soils were treated with organic (maize stover (MS) at 10xa0t ha−1, farmyard manure (FYM) at 10xa0t ha−1) and inorganic fertilizers 120xa0kg N, 52.8xa0kg P (N2P2), N2P2u2009+u2009MS, N2P2u2009+u2009FYM, a control, and a fallow for over 30xa0years. We examined 16S rRNA gene and 28S rRNA gene fingerprints of bacterial and fungal diversity by PCR amplification and denaturing gradient gel electrophoresis separation, respectively. The PCR bacterial community structure and diversity were negatively affected by N2P2 and were more closely related to the bacterial structure in the soils without any addition (control) than that of soils with a combination of inorganic and organic or inorganic fertilizers alone. The effect on fungal diversity by N2P2 was different than the effect on bacterial diversity since the fungal diversity was similar to that of the N2P2u2009+u2009FYM and N2P2u2009+u2009MS-treated. However, soils treated with organic inputs clustered away from soils amended with inorganic inputs. Organic inputs had a positive effect on both bacterial and fungal diversity with or without chemical fertilizers. Results from this study suggested that total diversity of bacterial and fungal communities was closely related to agro-ecosystem management practices and may partially explain the yield differences observed between the different treatments.

Modification of P availability by endogeic earthworms (Glossoscolecidae) in Ferralsols of the Malagasy Highlands

Low phosphorus (P) availability in Ferralsols of the Malagasy Highlands is a major limitation to crop growth. Direct seeding mulch-based cropping practices which were adopted in the region to improve and sustain soil fertility are known to favour earthworms’ presence. The mesocosm study aims to analyse the effect of an endogeic geophageous earthworm species on the soil P status. Total P content (Pt), NaOH-extractable P content, P ions (Pi) concentration (Cp) in solution and rapid and slow reactions of Pi in solution with solid phase were determined in two Malagasy Ferralsols. Both Cp and reactions rates were assessed in laboratory batch experiments using 32Pi labelling and isotopic exchange kinetics (IEK). The Pt values were 836 and 349xa0mg P g−1 in a clayey soil and a sandy–clayey soil, respectively. For both soils, NaOH-extractable organic P was significantly higher in earthworm casts than in parent soils, whereas Pt was unchanged. Also, the effect of earthworm ingestion significantly changed parameters of the IEK. In casts compared with the soil from which they were derived, the immediate isotopically exchangeable Pi (E1xa0min) increased by 116%, whereas relative rates of Pi release at the solid-to-solution with time were slightly lowered. The effect of earthworm ingestion on IEK corresponded to a transfer of slowly exchangeable Pi towards quicker Pi pools of exchange. However, according to the literature, the increase in E1xa0min remained below the critical level for optimal growth, stating that the soils remained P-deficient even in the presence of active and numerous earthworms.

Ecological interactions within the biodiversity of cultivated systems

Various types of biodiversities can be found within the cultivated plot and in its surrounding environment: plant, animal and microbial biodiversities; aboveground and belowground biodiversities; productive, resource, destructive biodiversities, etc.

Rock - Stone and "Soil - Earth": Indigenous Views of Soil Formation and Soil Fertility in the West Indies

Scientific investigations are conducted without blinders on. While the goals of our investigations tend to lead us from point A to point B in targeted data collection, sometimes information that is tangential, yet undeniably fascinating, falls into our laps. Such was the case for us during the course of botanical, agronomic and pedological investigations conducted in the West Indies during 1981-1986. This paper is based on information collected during informal interviews with local, family farmers from the islands of Martinique and Saint Lucia. Two sorts of farming system coexist all over the Lesser Antilles (see Peeters 1976):