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CROP DIVERSIFICATION

Crop diversification is the practise of cultivating multiple crops on a farm. Crop diversification often takes the form of crop rotations or intercropping. It is considered one of the most feasible, cost effective and efficient ways of reducing the uncertainties in farm yield brought on by climate change impacts. The purpose of crop diversification is to increase resilience to uncertain impacts, improve soil fertility, reduce the impacts of pest and disease and ensure a more stable crop yield.  These themes are explored further below.

Soil fertility: Soil fertility underpins the productivity of a farm. For soils to be fertile, they must supply sufficient Image removed. amounts of the nutrients required for crop growth (e.g. nitrogen, phosphorus, potassium, calcium and magnesium) and have sufficient organic matter to retain water. In monocultures, soils can become depleted in nutrients and water as all the plants on the plot have the same requirements under the same conditions. If plants species have trade-offs between their abilities to acquire different nutrients, with each species being better at acquiring some nutrients but poorer for others, then a diversity of plant species is essential for the long-term accrual of the multiple elements that are required for a soil to be fertile.

 

 

Yield stability: Crop diversification provides farmers with an approach to reduce variation in crop yields in response to climate impacts. Crop rotations and inter cropping can increase the probability of a farm harnessing favourable growth conditions while reducing the impacts of crop failures. Increased production from diversified cropping systems and increased production stability often lead to improved farmer income

Pest and disease: Different crops differ in their tolerance to disease and pests. By rotating crops that have different tolerances to disease, farmers can minimise the likelihood of total crop failure. Crop diversification improves pest and disease resilience by increasing natural enemies of insect pests, breaking disease cycles, suppressing weeds and volunteer crop plants and modifying the microenvironment within the crop canopy.

Possible crop diversification interventions relevant for the Pacific include:

  • Increasing within field diversity: Within field diversity can be achieved by planting crop mixtures and multiple crop varieties on the same field. Establishing diverse plantings at the field margins is also important.
  • Crop rotation: Crop rotation involves farming a sequence of crops and cover crops grown in a specific field. Rotation designs should include multiple crop families and should be a mix of short- and long-term crop fertility needs. This would disrupt weed and disease cycles and optimize crop production.
  • Intercropping: Intercropping involves two or more crops grown in close proximity which produce beneficial interactions. Intercropping can be achieved by growing crops in alternating rows (row intercropping), growing crops in larger alternating strips (strip intercropping), growing crops together with no distinct row arrangement (mixed intercropping) or by planting a second crop into a standing crop at the reproductive stage (relay intercropping). Special attention should be given to the spatial arrangement, plant density and expected maturity dates of selected crops.
  • Cover crops: Cover crops are often used to protect the soil from erosion during times when a field is not under production. Crops that are easy to plant, establish and control should be selected.
  • Relatively easy to achieve once the planning phase is complete.
  • Increases adaptive capacity of cropping land.
  • Instills wider tolerance to climate change impacts improving resilience of cropping land.
  • Crop diversity facilitates multiple ecological benefits and services (e.g. stable food production, increased yield, income stability).
  • Diversity can complicate farm management requiring research input, careful planning, crop supply and active management of multiple crops.
  • Multiple crops potentially require different infrastructure for planting and harvesting as well as chemicals for treating pests and diseases.
  • Can impact short term commercial productivity and financial returns.
Indicative cost

Crop diversification implementation is low cost although may also impact short term financial returns from farming. Whilst providing cost estimates is difficult given the broad range of influencing factors across the Pacific, the below table outlines the key components that should be taken into account when estimating an crop diversification project budget for a specific location.

Components

Unit
(A)

Number of units (B)

Unit Cost
(C)

Budget
(B x C)

Establishment Cost

        
  • Land (if not already held)

e.g. km2

      
  • Planning and design including community outreach

e.g hours

      
  • Materials (e.g. plants)

e.g number

      
  • Labour

e.g. hours

      
  • Reporting to donor (if required)

e.g. hours

      

Ongoing Cost

        
  • Maintenance Cost (materials and labour)

e.g. number and hours

      
  • Reporting and Monitoring

e.g. hours

      

Crop diversification is compared against mono cropping techniques.  Monocropping techniques focus on planting one crop which is then all harvested at the same time:

  • Over time monocropping tends to change the system to be unproductive by unbalance of nutrients like Nitrogen and Phosphorus.
  • Monocropping generally requires high levels of fertilizer and pesticide use can lead to pest and diseases developing resistance.
  • Monocropping is less resilient to change as if the single crop is affected then farm production can be drastically reduced.
On-ground impacts that the EbA option addresses
Decreasing agricultural yield
Increased prevalence of crop disease

Case study

Crop Diversification for sustenance farming

Pacific Island Countries

Crop diversification has long been practiced and researched in Pacific countries as a way of sustenance farming. A few of the countries and their practice are mentioned below:

  • A study in 2010-2012 showed that PNG highlands practiced coffee intercropping with food crops. This practice increased food security and cash incomes for the farmers. Another study in West New Britain (PNG) noted that farms tend to be diversified into cash crops like vanilla and betel nut between palm oil plantations requiring less land and labour to increase household income. This helped the farmers to sustain their families through fluctuations in palm oil prices.
  • A 1992 study showed that farmers in Tonga and Western Samoa adopted diversification strategies utilising taro, sweet potato, cassava and yam, along with a range of vegetables, fruit, fish and livestock to achieve sustenance farming.
  • A 2020 study in Fiji, showed that sugarcane farmers who adopted crop diversification approaches were able to achieve 45% more profitability than the farmers dedicated to sugarcane farming.

    Reference: Food security and small holder farming in Pacific Island countries and territories: A scoping review, https://journals.plos.org/sustainabilitytransformation/article?id=10.1371/journal.pstr.0000009 and Benefits of crop diversification in Fiji's sugarcane farming, https://onlinelibrary.wiley.com/doi/full/10.1002/app5.291