Organic mulch is applied in Almond fields to provide a permanent surface cover that protects the soil against soil erosion, reduces evaporation and limits the growth of weeds. This makes that less ploughing is needed under Almond trees that are normally ploughed 3-5 times per year if no mulch cover is present. The material used for mulching can be diverse. Most feasible are straw or bark and wood chips from pruning residues from almonds and forest species (mostly pines). Alternatively, alpha-grass can be used as mulch. Mulch can best be applied late spring or early summer in order to maintain soil humidity of spring rainfall. Mulch should come mixed and homogenised. It is spread around trees by a mechanical spade or by the arm of a caterpillar. A layer of maximum 3-5 cm of mulch should be applied for economical reasons.
Purpose of the Technology: The ultimate goal of organic mulching under almond trees is to maintain soil water through a reduced evaporation and reduce soil loss by erosion. A mulch covers reduces soil erosion by 1) reducing raindrop impact, 2) increasing water infiltration, 3) increasing surface storage, 4) decreasing runoff velocity, 5) improving soil structure and porosity, and 6) improving the biological activity in the soil. Mulching prevents off-site effects of erosion like flooding, damage to infrastructure and siltation of water reservoirs, while maintaining or slightly increasing crop productivity. The mulch results in a higher soil roughness, a better infiltration of water into the soil, and so also in a reduced runoff. The mulch also has a favorable effect on soil quality since the organic material of the mulch will slowly decompose and provide nutrients to the soil. The decomposing part of the organic mulch will increase aggregation and soil structure through the production of organic compounds (e.g. humic acids). The reduced necessity for ploughing of the Almond fields will result in less fuel use and labour as well as reduced emission of CO2. In addition, the mulch cover prevents weeds to grow and so less competition from weeds will occur and less herbicides are needed.
Establishment / maintenance activities and inputs: The establishment of mulching depends on the material used for mulching. Given its availability, the easiest is the use of pruning residue from Almond trees. Almonds are pruned in autumn, and residue can be chopped and applied directly or stored in the field until early spring. Residues are chopped and spread around the tree stem and if enough material is available between tree stems. Alternatively, and depending on availability, pruning residue of pine trees or alpha-grass can be used. Pine tree residue should come from nearby forest stands and need to be chopped just like the almond pruning residue in spring. Litter from the forest floor should not be used as this will cause damage to the forest. Alpha-grass is very common in the region and should be harvested in winter in the fields surrounding the cultivated area without destroying the plant allowing it to regenerate. The alpha-grass does not need to be chopped and can be put around the tree stem of the almond trees.
Natural / human environment: The technology is feasible for soils of shallow to medium depth (between 20-60 cm), and with gentle to moderate slope gradients (2 - 8%). The climate is semi-arid with a mean annual rainfall around 300 mm. Droughts, centred in summer commonly last for more than 4-5 months. Annual potential evapotranspiration rates larger than 1000 mm are common. The production system is highly mechanised and market oriented but depends strongly on agricultural subsidies. All cropland is privately owned.
Location: Guadalentin catchment, Murcia, Spain
No. of Technology sites analysed:
Spread of the Technology: evenly spread over an area (approx. < 0.1 km2 (10 ha))
In a permanently protected area?:
Date of implementation: 10-50 years ago
Type of introduction
| Specify input | Unit | Quantity | Costs per Unit (n.a.) | Total costs per input (n.a.) | % of costs borne by land users |
| Equipment | |||||
| Per (to cut pruning residue) | piece | 1.0 | 4761.0 | 4761.0 | 100.0 |
| Total costs for establishment of the Technology | 4'761.0 | ||||
| Total costs for establishment of the Technology in USD | 4'761.0 | ||||
| Specify input | Unit | Quantity | Costs per Unit (n.a.) | Total costs per input (n.a.) | % of costs borne by land users |
| Labour | |||||
| Cut alpha-grass (optional) | person/days | 4.0 | 95.25 | 381.0 | 100.0 |
| apply mulch of alpha-grass, almond and pine tree pruning residue | person/days | 4.0 | 10.0 | 40.0 | 100.0 |
| Equipment | |||||
| Machine use | person/days | 0.5 | 88.0 | 44.0 | 100.0 |
| Fertilizers and biocides | |||||
| Mulch | tons/ha | 15.0 | 55.53333 | 833.0 | 100.0 |
| Total costs for maintenance of the Technology | 1'298.0 | ||||
| Total costs for maintenance of the Technology in USD | 1'298.0 | ||||
