Effects of conservation and standard tillage on soil physico-chemical properties and overall quality in a semi-arid agrosystem

Shifting agricultural operations to more sustainable management practices is needed in the face of a changing climate. In this study, the short-term effects of three tillage systems (no-tillage, minimum tillage, and conventional tillage) on a wide selection of soil properties in a semi-arid agrosystem of eastern Tunisia were assessed. The studied soil properties included saturation percentage, bulk density, penetration resistance, mean weight diameter, electric conductivity, soil reaction, soil organic matter, carbonates, available phosphorus and exchangeable potassium. The impacts of tillage systems on soil quality indices (SQI) developed based on the total set of properties (SQI-T), or a minimum set (SQI-M) selected through principal component analysis, were also investigated. Relative to conventional tillage, no tillage increased bulk density, penetration resistance and electrical conductivity, whereas minimum tillage affected only saturation percentage and pH. No-till and minimum tillage did not enhance soil quality relative to conventional tillage. The SQI-T and SQI-M were highly correlated (r=0.93) to each other suggesting that the outcomes of the two indices are comparable. Principal component analysis efficiently selected the most influential indicators of the effects of tillage systems on soil quality. Farmers in the study region are encouraged to consider minimum tillage during the early years of transition from standard to no-tillage systems to avoid rapid decline in soil quality and consequent yield loss

Petite motorisation et exploitations maraîchères de taille limitée du Sahel tunisien Partie 2: Evaluation sur le terrain des performances et des coûts de préparation du sol

Low Power Mechanisation and Small-scale Vegetable Production in the Tunisian Sahel Region. Part 2: On the Field Evaluation of Performances and of Soil Preparation Costs. In this study, it was investigated to what extent low power mechanisation could be introduced in vegetable production in the Tunisian Sahel region by evaluating its performance (labour input and field efficiency) by means of field experiments in which different traction equipment was used for carrying out several cultivation operations. Furthermore, costs per unit area for soil preparation in both sandy clay and clayish sand were calculated for four different power classes and for small fields. The results showed that two wheel tractors had a real labour input for scuffling between plant rows ranging from 11.3 h/ha to 18.7 h/ha. These inputs ranged from 5.5 h/ha to 6.7 h/ha for tied crops. For mowing, the two wheel tractor had labour inputs of 17.3 and 14.2 h/ha for the first and the second cut, respectively, while for potato digging, the first and the second passage of secondary tillage these values were 11.5, 14.3 and 10.4 h/ha, respectively. Superficial soil preparation by means of a four wheel tractor gave rise to values between 2.7 and 3.5 h/ha. With respect to the cost estimation for soil preparation, the lowest costs were obtained by means of the low power mechanisation. Similar conclusions were drawn for the field efficiencies for the operations investigated. In general, these efficiencies were above 70%

Petite motorisation et exploitations maraîchères de taille limitée du Sahel tunisien. Partie 1: Etude diagnostique

Low Power Mechanisation and Small-scale Vegetable Production in the Tunisian Sahel Region. Part 1: Inquiry. In this study, it was investigated to what extent low power mechanisation could be introduced in vegetable production in the Tunisian Sahel region by means of an inquiry held among local vegetable growers and at the mechanisation market. Data were collected as to acquire precise information on exploitation characteristics (number and area of the parcels, crops grown, adopted mechanisation, etc.) and on equipment available at the local market (type, power, etc.). The results demonstrated the predominance of small exploitations, which mainly consist of two separate parcels on which several crops are grown. Most exploitations were managed by young and well experienced farmers. Only soil preparation was found to be entirely mechanised. Mechanisation was mainly based on relatively large and high power tractors (typically more than 50 kW). The local machinery market of low power mechanisation was found to offer 5 to 7 kW motor hoes, 6 to 10.5 kW walking (two wheel) tractors and two types of small (four wheel) tractors of 12 and 16 kW. It was observed that equipment was available for all cultivation operations that are nowadays mechanised, while other operations as scuffling, ridging up, and phytosanitary treatments could still be mechanised

Etude comparative de quatre niveaux de puissance de traction en travail du sol des petites exploitations maraîchères

Comparative Study of Four Traction Power Levels for Seed Bed Preparation in Small-scale Vegetable Production. The effects of four different traction power categories on soil structure was measured in the field during seed bed preparation experiments in a sandy clay soil and a clayish sand soil used for vegetable production. The power categories investigated corresponded to a standard tractor of 59 kW, a medium power tractor of 33 kW, a low power tractor of 22 kW and a two-wheeled tractor of 6 kW. In each experiment, seed bed preparation was carried out using a mouldboard plough and a rotary cultivator, respectively. Soil structure was characterised by measuring the resistance against vertical penetration of a cone by means of a penetrometer and the apparent dry density by means of a cylindrical densimeter. For both soils, the results showed a porous soil state without any significant difference among the four power levels. All different methods of tillage used were giving the same structure in the top layer. The soil crumbling was done using a PTO driven cultivator. Also, the measured parameters did not differ significantly over the depth of the worked area. Also the differences in work speed and equipment used don't have any influences on the measured parameters. The complexity asks for a detailed technical-economical investigation in order to define the advantages and disadvantages of the use of small power mechanisation for seed bed preparation

Comparative Study of the Impact of Two Mechanical Perforation Densities on the Behavior of a Sandy Soil

The effects of mechanical perforation densities by extracting soil cores through an aerator Vertidrain with a working width of 1.6 m and equipped with hollow tines spaced of 65 mm, were studied on a sandy soil of a grassy sward in the Golf Course El Kantaoui in Sousse (Tunisia). The mechanical aeration was performed at two densities: 250 and 350 holes/m2. The cone penetration resistance and soil water infiltration were measured. These parameters were performed at initial state before aeration (E0) and then on the 10th, 20th and 30th day after aeration. These results showed that perforation density of 350 holes/m2 had a positive effect on the soil by reducing its cone resistance to penetration compared to the initial state (Rp = 14.8 daN/cm2). At 5 cm depth the decrease in resistance to penetration was 34% and 43% on the 10th and 20th day after aeration, respectively. However, on the 30th day after aeration the soil resistance to penetration tended to grow and its value compared to the initial state decreased only by 21 and 26%, respectively, at 5 and 15 cm of depth only by 10% and 9% with 250 holes/m2 density. The soil water infiltration made a good improvement after aeration compared to the initial state. This parameter increased from 4.8 cm/h to 8.3, 10.9 and 13.1 cm/h with 250 holes/m2 density and to 10, 12.9 and 14.8 cm/h with 350 holes/m2 density on the 10th, 20th and 30th day following the aeration

Effets des outils de reprise de labour sur l'état structural du sol et le rendement d'une culture de pomme de terre

Effects of Shallow Plowing Tools on the Soil Structural State and the Potatoes Crop Yield. Effects of three tillage tools (disc harrow, teeth harrow and rotary cultivator) on two physical characteristics of silt-sandy soil (resistance to the penetration Rp and voluminous mass Mv) and their potential influence on fresh matter and total yield of potato were studied at the experimental field of the Horticultural School, Chott-Mariem (Sousse). Results show that the three tools reduce the resistance penetration and the voluminous mass of soil tilled especially using disc harrow at 15 cm depth (Rp= 2.8 daN/cm2 and Mv= 1.03 g/ cm3) compared with non tilled soil (Rp= 11.4 daN/cm2, Mv= 1.43 g/cm3). Highest fresh matter yield was obtained (at 130 days) after soil ploughing with disc harrow showing an average increase of 33, 24, 18 and 15% respectively for leaves, tubercles, stems and roots compared with other tools. Best tubercles yield was also reached using disc harrow showing an increase of 21% and 24% compared, respectively, to teeth harrow and rotary cultivator