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Adaptive Research and Field Market Studies

Research support to FAO-EC Project: GCP/INT/952/EC-MOZ - Improved Integration of Root and Tuber Crops in CFSAM Food Balance Sheets

General Objectives:

  • Improved understanding of food security.
  • A rapid assessment methodology to be derived that will improve present levels of understanding of contribution of roots and tubers to food security. Presently:-
    • MADER estimates cassava area at 1 million ha at average yields of 5-6 tha-1
    • Other estimates suggest average yields of 10-18 tha-1

Main Findings:

1 Average yield estimates for small plots, taken from weighing tubers of 1 plant carefully selected by the cassava harvester were as useful an estimate as the average weight determined by weighing a random sample of 10 plants.

2 Point- to- plant system is the best system to determine plant density where line planting (regular rows) has not been used.

3 Land forming viz mounds or banks and intercropping don’t affect the form of the calculation but might affect yield per plant.

  • Cassava is by far the most important of the roots and tubers in terms of area planted and production obtained.
  • Systems used are highly variable with a variety of choice viz -sweet or bitter; commercial or subsistence; one year or two or all-year -round harvesting.
  • The choice of system determines the choice of pattern of planting and harvesting. Sweet varieties are usually found in 1 yr, block planted systems.
  • The systems are obvious to the eye of the trained observer as cassava lends itself to rapid system recognition from a distance through the strength and height of canopies as shown in the pictures.
  • TRANSECTS may identify the frequency of occurrence/importance of each system.
  • Annual production is a function of harvestable area X yield per unit area.
  • Yield per unit area is a function of plant density X weight of tubers per plant (dry or fresh).
    • Annual Production (AP) = Area Harvested x Yield Unit Area
    • AP 1 yr system = Total Area x Yield per Unit Area
    • AP 2 yr system = Area of 2nd year plants x Yield per Unit Area
    • AP All-yr round system = Total area x plant density x 12/ ?m x Yield per harvested plant, where ?m is the average age of the harvested plant.

Results show that the correlation coefficient for the relationship between the weight of tubers from a well selected single plant and the average weight of tubers from 10 randomly selected plants is 0.939 at p<0.001, as demonstrated in the graph below.

Correlation coefficient graph

Crop planted and harvested together in same season, Mozambique   , yearly intervals  
Plate 1: The crop is planted and harvested together in the same season, the whole process being completed in one year.   Plate 2: Crop on the left planted during the planting season a year before the plants on right of the photograph and will be harvested.  
Cutting planted at various times during the year  

Plate 3: Cuttings have been planted at various times during the year and exhibit the full range of ages from 0 to 24 months in the same plot.


Download the Cassava Guidelines


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