SWBP: Land Degradation

SWBP is Solutions for the World's Biggest Problems;
a 2007 book I'm reading, edited by Bjorn Lomborg, of the Copenhagen Consensus Center
Ch. 8, Land Degradation, by Ian Coxhead and Ragnar Oygard
pp. 146-159

Stop treating dirt like dirt

There's a big long definition: in short, it's reduction in in soil quantity and quality as an input to agricultural crops. Watershed function and other off-site effects figure into it, though, too.

It's measured by pH, organic matter content, plant-available nutrients, porosity, grain size distribution, water permeability and retention capacity, topsoil depth, presence of toxic chemicals (to plants or plant consumers), etc. -which varies with depth and horizontally, as well. All these characteristics interact. I'm no soil scientist, but my alma mater,UCD, I know has a pretty good program in it.

This chapter begins with a crash course in farming:
Crop yields depend on water, fertilizer, seed variety, and crop mgmt. practices, in addition to soil quality. (I think they forgot weather; i.e. sunshine, lol) In other words, it's not a good proxy for measuring degradation, but trends can still be seen.

Nutrient levels are improved by adding manure or fertilizer; acidity is countered with lime; and drainage and irrigation improve water availability.

Likewise, degradation (loss of topsoil and nutrients) occurs through: 1. soil erosion through seedbed preparation leaving the soil vulnerable to wind, rain impact, and surface water flows. Or, through intensive grazing that also lowers the amount of protective vegetation. 2. "soil compaction and crusting" 3. nutrient mining by removal of crops without replacing it with manure, fertilizer, or plant residue. 4. salinization under arid conditions, when salts are not washed away. 5. waterlogging from poorly-controlled irrigation. 6. there's also pollution and alkalization.

Characteristics such as slope, soil texture, climate, and cropping pattern affect soil resilience. Some of the above problems are less irreversible than others.

Off-site effects include siltation of dams and waterways, nutrient runoff causing eutrophication, pesticide runoff, windblown soils, and released CO2 and CH4 (contributing to global warming).

FACT: No developing country has installed a system for monitoring soil quality at a national scale. Little is known about status, and even less about trends, or what extent the degradation is human-caused.

What is known is that some environments have experienced a 50% or higher reduction in crop yields. Experimental plots have yielded data, but the basis for extrapolation to farmer's fields is weak. One study, with contributions by 250 experts, estimated that 560 million hectares of land had been degraded since the 1940's, or 38% of the total. A review of 16 studies shows that soil quality has remained fairly stable for 75% of the world's arable land, but widespread and accelerating on the rest. Specifically, 5-8 million hectares (ha's) have gone out of production each year (since?). These are primarily lands on the margin of cultivation, such as at the edge of deserts, or steeply-sloping or high-altitude areas.

Temperate lands are more resilient, so the problem exists primarily in poorer societies of tropical and sub-tropical areas where property rights are weakly defined, information systems are weak, and managerial capacity is low. Income from the land accounts for a greater share, making them more vulnerable to this problem, as they have fewer resources to combat it. Land tenure insecurity and credit market failures lead to faster soil mining.

The FAO predicts an increase in farmland area over the next 25 years of 8%, much from the clearing of tropical forests, which will have high local costs but will not threaten food supply or agricultural commodity prices.

The solution, in basic terms, is to maximize vegetation cover to prevent erosion; replace the removed nutrients; prevent the accumulation of harmful substances; and put in structures to reduce the speed and volume of water flow over the soil (i.e. terraces, bunds, vegetation strips).

5 market-based policies that offer economic incentives to achieve this are as follows:
1. Price and Trade policy reforms. E.g., no explicit or implicit subsidies on practices that increase land degradation, or taxes on activities that tend to reduce it. Abandoning or reducing protectionism is good, too, despite the short-run costs of policy implementation, market-adjustment, and revenue-losses to governments. They are minuscule in relation to the long-run benefit streams.

Crops that contribute to land degradation will be grown in countries and environments with lower environmental costs, say Ian and Ragnar.

2. Poor rural households "face severe liquidity constraints and have very high discount rates." This book mentions discount rates in every single chapter; I still can't definitively say what they are, although I can say it has to do with expectation for the future. It's an important concept, obviously, but I just didn't get it, earlier. The whole book is premised around benefits and cost ratios at discount rates of either 3 or 6 percent. Hmm. It's just this kind of ambiguity that makes an exciting excercise more "dismal." My fault?

Anyway, the improved functioning of imperfect credit/financial markets will facilitate land-conserving investments, while also probably increasing the land area to be cultivated, leaving the overall picture ambiguous. It's a solution, with a caveat.

3. The solution has to be culture-specific. In areas of low population density, they use up the land, and move on to a new plot. In Ethiopia, secure land rights might induce investments, such as in terracing. Elsewhere, investments can be a means of obtaining permanent land use rights. In Ghana, women, who have less rank, leave the land that they farm fallow for less time, based on the assumption that land which is actively cropped is less likely to be reallocated. Entire communities can be empowered to manage something like a rangelands as a commons, to reduce grazing intensity. Legal systems need to work, to give certificates of land title meaning. Soil qualilty is hard to observe, and be poorly captured in land transactions.

4. Technology. Nutrient replacement costs, for example, can be reduced, and returns to nutrient inputs (yields) can be raised. Less land is thus necessary for the same output. Marginal agricultural land can also be retired by migration from farming to industry, like what happened between '85-'95 in Thailand.

5. Direct land use interventions, such as conservation areas, land-use zoning, or public reforestation projects. China, for example, is spending 40B USD on almost 15 million hectares. Some countries pay farmers to desist. Bribery is messy, though (cost of monitoring and enforcement). Improved water management and installation of drainage systems, ending water and energy subsidies that encourage water wasting, are all good.

Attempting a benefit:cost analysis, they say, is futile, due to the heterogeneity of the projects, but rates of return can be presented. I'll give 'em to you if you ask. I'm tired.

By the way, Eutrophication is:

noun
Excessive nutrients in a lake or other body of water, usually caused by runoff of nutrients (animal waste, fertilizers, sewage) from the land, which causes a dense growth of plant life; the decomposition of the plants depletes the supply of oxygen, leading to the death of animal life; "he argued that the controlling factor in eutrophication is not nitrate but phosphate"

You're welcome, lol.