1 / 20

CONTOUR RIDGES and NARROW & BROAD BASED TERRACES Ridge & furrow

CONTOUR RIDGES and NARROW & BROAD BASED TERRACES Ridge & furrow Slope on which possible is limited by soil type (strength / infiltration) & by tractor stability if mechanised

harry
Download Presentation

CONTOUR RIDGES and NARROW & BROAD BASED TERRACES Ridge & furrow

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CONTOUR RIDGES and NARROW & BROAD BASED TERRACES • Ridge & furrow • Slope on which possible is limited by soil type (strength / infiltration) & by tractor stability if mechanised • Construct on grade (0.25 - 0.5%) on less permeable soil or steeper land, otherwise if medium to high infiltration soil and/or high ridges, construct on the contour • Maximum slope depends on soil type (perhaps up to 10 or 20% from calculations - but in practice often limited to slopes less than 2%)

  2. Larger ridges may be semi-permanent ("splitting" the ridge every other year or so); common technique is to place residues into lines, then ridges constructed over them (2 to 4 rows /ridge) • plant drought resistant crop on side • It is good practice to provide open field drains at intervals down field as insurance against breakages • Can use plough to construct - disk plough best • Survey "contours" every 10 to 20 m then fill in between (by pacing or using tractor settings); ridges will then run more-or-less parallel; fill in the irregular spaces (with crop or fodder grasses or fodder legumes)

  3. Breakages will occur: • if ridges are not on the "contour" • if soil not consolidated • Danger of breakage have led some soil conservationists to prefer not to use

  4. Tied ridges

  5. Ties recommended at 2 to 5 m spacing along furrows (not as high as ridge tops) to prevent breakage and improve storage • Special cultivators are available for tractors, e.g. Chinene & Pauwelyn (1991)

  6. Tied ridges in Zimbabwe with crops planted in furrow: vertisol soil, 1.5 m spacing, 0.3 m high, parallel to contour, ties at 5 to 7 m, fertiliser next to furrow

  7. Broad beds

  8. Broad-bed & furrow mainly for impermeable soils, especially vertisols Broadbed-makers sometimes used, e.g. those developed by the old International Livestock Centre for Africa (now ILRI) consists of two traditional wooden frame ploughs & two winged, metal ploughshares made to throw soil in opposite directions, scoop soil towards middle, creating a mound which are manually formed into beds 15 cm high x 80 cm wide separated by 40 cm wide furrow

  9. Beds normally made by hand so 40% of labour requirement is conserved. Earlier planting is possible because soil dries out easier. Longer duration varieties or 2 short duration crops are possible.

  10. Ridge and furrow used as water harvesting structures

  11. Cultivated terraces • Like contour ridges but on a larger scale (4 to 7 m?) • Usually considered as terraces in the books more like large ridges • On mechanised farms, blade on tractor or bulldozer can be used. Possibly oxen could be used. • Use graded furrows on more impermeable soils • Plant lower sides of furrows with more drought sensitive crops (behaves rather like water harvesting system)

  12. Crops grown in channel and on bank but channel slopes to drain water into waterway

  13. Constructed on the contour

More Related