Geochemical study of the rehabilitation of a shallow anoxic reservoir, in volcanic terrains, under semi-arid climate, in Cape Verde Archipelago

Poilão dam reservoir (Cape Verde Archipelago) is in critical conditions, owing the excessive silting up, the high concentration of nitrates and the pronounced anoxia all over the lake. Considering that the most suitable remediation strategy is the removal of the bottom sediments where nutrients are preferentially concentrated, we have done a geochemical study, in order of evaluating their suitability to agricultural use. Analyses indicate that sediments are rich in a few key nutrients, when compared with parent soils. Thus, adding suitable sediments to nearby degraded soils can improve food crops for smallholder farmers living in close proximity to this system.

THERMAL EFFICIENCY OF INDIVIDUAL SHELTERS FOR GIROLANDO CALVES IN BRAZILIAN SEMI-ARID REGIONS

The objective of this research was to evaluate the thermal efficiency of roofs used on individual shelters during milk-feeding stage of Girolando calves. The research was conducted at a farm located in a dry region of Pernambuco state, Brazil. The experimental design was completely randomized, with 27 Holstein × Gir dairy crossbred calves housed in shelters with three roofing materials (fibre cement tile, recycled tile, and thatched roofs). The recycled tiles and thatched roofs provided reductions of 18.7 and 14.6% in radiant thermal load, respectively. Regardless the roofing material, all animals increased their respiratory rate to maintain thermal equilibrium.

Effect of trees in the soil nutrient concentration and pasture produtivity in Mediterranean silvo-pastoral systems

Silvo-pastoral are mixed systems of trees and grass, which have been proposed as a means to extend the benefits of forest to farmed land. Agro-forestry systems under semi-arid Mediterranean conditions, called montados in Portugal and dehesas in Spain, cover substantial areas in the world. These silvo-pastoral systems are the most extensive European agro-forestry system, as they cover 3.5–4.0 Mha in Spain and Portugal. Long-term studies are essential to assess the magnitude of the temporal nutrient flow dynamics in terrestrial ecosystems and to understand the response of these systems to fertilizer management. In order to implement the conservation task and recovery of resources through silvo-pastoral systems it is necessary to know and correct potential limiting factors, especially the soil factor, and this requires agronomic knowledge as well as the implmentation of the available new technologies. In this context, this task aims at a better understanding of the contribution of the two components of montado ecosystem (trees and herbaceous vegetation) on the soil nutrient and water dynamics, that allow for the interpretation of the variability of pasture dry matter yield and help the farmer in the management of tree density. Collaterally the task will evaluate and calibrate new technologies that simplify the monitoring of soil, grassland, trees and grazing animals.

The flora and vegetation in an area of the Caatinga in Taperuaba, Sobral, Ceará state, Brazil

The Caatinga, covering about 800.000 km2, is the predominant vegetation type of the semi-arid region of Brazil. The Caatinga biome comprises several phytophysiognomies and floristic compositions, with many endemic species, especially in Fabaceae, Cactaceae, Euphorbiaceae, Bignoniaceae e Combretaceae. Despite considerable advances, the Brazilian semi-arid needs more studies and inventories of biodiversity, especially the Ceará state. On the basis of these considerations, the present study aims to identify the flora and vegetation, in order to characterize the phytophysiognomy in an area of the Caatinga, in locality of Taperuaba, municipality of Sobral, Ceará, Brazil. Field work was conducted in March 2015 and 2016 respectively, in three transects. The life-forms were established in accordance of Raunkiaer´s system. The floristic list is composed of 87 species, distributed in 66 genera and 36 families. The flora comprises 22 Brazilian endemic species. The most representative family was Fabaceae with 15 species, followed by Malvaceae (7) Convolvulaceae (6), Euphorbiaceae (5) and Poaceae (5). The biological spectrum had a high proportion of therophytes (29,9%), chamaephytes (29,9%) and phanerophytes (26,4%). In the area were identified two phytophysiognomies: outcrops communities highlighting succulent phanerophytes (Pilosocereus chrysostele (Vaupel) Byles & G.D. Rowley subsp. cearensis P.J. Braun & Esteves and P. gounellei (F.A.C. Weber) Byles & Rowley), chamaephytes (Encholirium spectabile Mart. ex Schult. & Schult. f. and Lepidaploa chalybaea (Mart. ex DC.) H. Rob.) and therophytes (Mitracarpus baturitensis Sucre), mixed with communities including small trees and shrubs on deeper soil, composed of Cereus jamacaru DC., a succulent phanerophyte, and many woody phanerophytes, such as Cordia oncocalyx Allemão, Crateva trapia L., Mimosa caesalpiniifolia Benth., M. tenuiflora (Willd.) Poir., Poincianella bracteosa (Tul.) L.P. Queiroz and P. pyramidalis (Tul.) L.P. Queiroz.

Local Understandings of Soil Fertility, Rainfall and Conservation Agriculture in Laikipia, Kenya: A Qualitative Analysis.

Conservation Agriculture (CA) is mostly referred to in the literature as having three principles at the core of its identity: minimum soil disturbance, permanent organic soil cover and crop diversity. This farming package has been described as suitable to improve yields and livelihoods of smallholders in semi-arid regions of Kenya, which since the colonial period have been heavily subjected to tillage. Our study is based on a qualitative approach that followed local meanings and understandings of soil fertility, rainfall and CA in Ethi and Umande located in the semi-arid region of Laikipia, Kenya. Farm visits, 53 semistructured interviews, informal talks were carried out from April to June 2015. Ethi and Umande locations were part of a resettlement programme after the independence of Kenya that joined together people coming from different farming contexts. Since the 1970–80s, state and NGOs have been promoting several approaches to control erosion and boost soil fertility. In this context, CA has also been promoted preferentially since 2007. Interviewees were well acquainted with soil erosion and the methods to control it. Today, rainfall amount and distribution are identified as major constraints to crop performance. Soil fertility is understood as being under control since farmers use several methods to boost it (inorganic fertilisers, manure, terraces, agroforestry, vegetation barriers). CA is recognised to deliver better yields but it is not able to perform well under severe drought and does not provide yields as high as ‘promised’ in promotion campaigns. Moreover, CA is mainly understood as “cultivating with chemicals”, “kulima na dawa”, in kiswahili. A dominant view is that CA is about minimum tillage and use of pre-emergence herbicides. It is relevant to reflect about what kind of CA is being promoted and if elements like soil cover and crop rotation are given due attention. CA based on these two ideas, minimum tillage and use of herbicides, is hard to stand as a programme to be promoted and up-scaled. Therefore CA appears not to be recognised as a convincing approach to improve the livelihoods in Laikipia.