Crops
Caution is advised, given the fact that statistics are of varying degrees of reliability and there are important differences between those from the main sources.
It is useful to start with the broad picture. The main crop in any country is cultivated for good reasons and is established as a farming system. Where there is a dominant crop, improvements related to its value chain usually offer the best opportunity of being an engine of growth. Leaving aside the main crop in strategy usually confines the strategy to limited improvements. There may be good reasons why this must be so but equally there are occassions where it is not given sufficient weight. The main crops being produced globally for trade are:

Based on FAO data
In terms of global production, the largest production is of sugar cane, followed by maize, wheat and rice. Yet, it is often statistically minor crops that are the centre of attention due to their impact on regions, consumers or incomes. Traditionally, the sugar and cereal crops are of relatively low value on a per ton or even per hectare basis.
But in area terms, the most important crops were:
wheat, maize and rice, followed by soyabeans, barley, sorghum, millet and seed cotton.
Based on FAO data
Farmers rarely only grow one crop. They tend to allocate their assets, land, labour and other, to a portfolio of activities and crops, some for subsistence and others for sale or barter. The main crop and conditions determine what farming system dominates but it is the analysis of the portfolio that is important in looking for ways in which production can be diversified or incomes increased.. One school of thought places emphasis on the main crop as being a potential engine of growth for Agriculture and the economy. While it is true that improvements in the chain of the main crop afford the largest possible impact, it is also true that such changes are difficult and do not alter the basic fundamentals.
It is difficult to diversify from the main crops and they are often needed for food security. At the same time dependence on one or a small number of commodities often makes producers vulnerable to changes in global commodity prices. Sometimes, there is no other way of increassing earnings and income from exports other than through Diversification into higher value crops is very often advocated without any clear basis for defining the higher value crops and taking account of the fact that the markets for the high value crops are far more limited than existing main crops. We have had to try to define what are higher value crops and long ago decided that the criteria has to be based on price although one problem area that has to be accounted for is sometimes you have to look at processed value. The price line that is used can be based on FOB in an export oriented project or at farm gate or wholesale.
There have been few higher value crops for which value chains have been prepared, the exceptions being mangoes, pineapples and bananas. An approach we have used is to calculate rates of return per hectare for different crops and to compare these rates of returns between different countries to assess comparative advantage. Again, surprisingly, despite billions of dollars spend, no aid agencies appear to have undertaken such an exercise. Studies on competitiveness are very likely to be aggregate academic exercises. They are useful for purposes of planning. Our in-house comparisons have been conducted as and where we could and are therefore only of indicative value. A number of decisions have to be made as to points at which income is measured.
In the course of implementing contracts, we have had repeated opportunities to look at markets, both, in developing and developed countries. For horticulture, we have helped undertake European wide market research and to advise potential exporters in developing countries on selling to them. We have also looked at India, Sri Lanka, Malaysia, Singapore, Indonesia, Thailand, Philippines and Cambodia. For hard fibres and geotextiles we have also looked at North america, Australia, New Zealand and Saudi Arabia. All our work has helped us to understand returns per ton, per hectare and what are low and high value crops.Thanks to the various market studies, over a period of time we have generated comparative data that can be updated and applied.
Crops covered by us are:
Barley Maize Rice Wheat Rye
Sorghum
Castor Coconut Cottonseed Groundnut Linsead
Maize Palm and Palm Kernel Rape Rice Bran
Safflower Sesame Soya Sunflower
Almonds Arecaut Brazil Cashew Hazle
Kola Peanuts Pecan Pistachio Walnut
Spices, Essential Oils and Oleoresins
Cardamom Chilli Cinamon Cumin Ginger Mustard Nutmeg Pepper Pimento Saffron
Tamarind Turmeric Vanilla
Cocoa Coffee Rubber Sugar Tea
Tobacco
Apples Apricots Avocados Bananas Berries
Cherries Durian Grapefruit Grapes Guavas
Kiwi Lemons Limes Lychee Mangos
Mangosteens Melons Nectarines Oranges Papayas
Peaches Pears Pineapples Plantins Plums
Pomelos Quinces Rambuttans Tangerines Tomatos
Watermelons
Artichokes Asaparagus Bok choy Broccoli Broad beans
Cabbages Carrots Cassava Celeriac Cauliflower
Cellery Cucumber Garlic Green beans Gourds
Lettuce Mushrooms Okra Onions Peas
Potatos Sweet potato Shallots Swedes Taro
Tubers Spinach Turnips
Abaca Coir Hemp Jute Kenaf
Sisal
Cotton Ramie Linen Flax Wool
Returns per hectare
We like to gather enough data to allow an analysis on returns per hectare. Below is one that we undertook in South East Asia in 2003 with some recent updating, and since some figures are out of date, it is only given in the form of illustrating what is required for purposes of analysis.

The above is the sort of data on crops in a particular country which is required to decide what crops are relatively of high value. With this information, potential markets can be explored and analysis undertaken of comparative advantage in supplying those markets. In any case, it also tells us where efforts should be concentrated to increase farmer incomes. It still does not mean that the largest crops can simply be substituted by higher value ones due to factors like physical pre-conditions, markets, support and infrastructure.
Of course, data above can tell us much more. For example, it tells us that efforts to increase productivity offer gains but the gains may not be enough to offset the fact that the commodity inherently offers poor returns. This is certainly true of rice, cassava, maize, wheat and sugar. It may be preferable to change varieties in the case of bananas, or to seek added value in the form of processing for coconuts and rubber and selling in different form as with organic brown rice with husks.
When looking at productivity, it is very tempting to observe that it is too low. Productivity can nearly always be said to be too low because improvements are allways possible. For example, it is almost de regeur to say that Cambodian rice yields are very low compared to others in the Region while we do not think that it is necessarily true anymore, especially not when net returns are taken into account. It is difficult to see the truth because aggregate statistics do not tell how many crops, wet or dry, and inputs. Moreover, the latter are varied and national averages are just that. It is even easier to use what has been achieved in controlled circumstances to achieve high yields to claim productivity is very low. Our approach is to take existing yield rates and those possible in sub optimal conditions and use both to calculate current and potential value.
The limitations on drawing conclusions from apparent productivity figures are posed by unreliability of basic data and the interplay of factors not understood. How else could you understand the data from Cambodia on maize or cassava production.
Cambodia Maize data is amazing
Based on FAO data
In the above chart, and it is even more dramatic in the case of cassava production in Cambodia, reports would have us believe that there is this near miraculous increase in productivity in latest years. Clearly, something needs explaining. Everyone just accepts the published data (all the Donors, the Government and FAO) and it may be true. If it is true, it makes arguments on low productivity in Cambodia absurd since when returns justify it, farmers have no problem moving up a gear or two. From one ton per ha, productivity is reported as having risen to over 3.5 tons per ha in a 5 year period.