Agriculture Reference
In-Depth Information
land. The government of the Philippines has stopped its fertilizer subsidy program,
replacing it with a balanced policy that promotes location-specific combinations of
organic and inorganic fertilizers. Turkey has tripled agricultural productivity in the
past 8 years using sustainable methods. In addition, extension workers are being
deployed to live in villages alongside the farmers who need their services. Thus
far, with 7500 technicians hired, 80% of the country's 35,000 villages are covered.
Open-channel irrigation is being converted to drip or sprinkler irrigation systems
through interest-free loans and 50% grants to farmers. Subsidies for fertilizer are
conditioned on soil analysis. Once the soil is analyzed and the farmer knows what
nutrients it needs, the government pays for the soil analysis and for a certain amount
of fertilizer.
Looking for innovative farmers and the “lighthouses” they create, and linking
their results to the type of soil where they work, is a key element of the analysis
provided in this chapter. The International Union of Soil Sciences World Reference
Base (IUSS-WRB 2007) system of soil classification will be used throughout to
define soil types being analyzed. Soil classifications are often not provided in the
soil fertility literature, and soil types in this chapter are therefore characterized at the
highest level of classification, the Reference Soil Groups (RSG). Only when possible
are qualifiers added, such as in the Dutch case studies.
2.3
RESULTS
2.3.1 S
emiarid
a
renoSolS
and
l
ixiSolS
in
Z
imBaBwe
Ncube at al. (2009) described farming systems in semiarid (av. 590 mm/yr rainfall)
southwest Zimbabwe. The soils were Ferralitic Arenosols, locally interspersed by
Aridic Arenosols. Farm sizes were 5 ha and smaller. Three types of farmers were
distinguished: better, medium, and poorly resourced. Drought-resistant pearl millet
(
Pennisetum glaucum
) was grown on 80% of the land. This 3-year study showed that
all farmers could, on average, not satisfy the nutritional demands of their households.
Total cereal production varied widely as a function of precipitation. All nutrient bal-
ances were strongly negative. Clearly, adequate ecosystem services are not delivered:
the food and fiber service is inadequate, while negative nutrient balances illustrate
worsening future conditions. Soil security is not assured, a conclusion also implicitly
presented by Tittonell and Giller (2012) in a broad review of smallholder agriculture
in Africa, stating that successful ecological intensification is only feasible when soil
nutrient stocks would be strongly increased. Current socioeconomic and institutional
conditions are not favorable to achieve this. Incorporation of legumes in the cropping
system can increase production levels (Giller and Cadisch 1995), particularly when
P is added as well. However, additional input by manure and chemical fertilizer is
indispensable (Adjei-Nsiah et al. [2008] working on Lixisols in Ghana, Ojiem et al.
[2007] working in West Kenya without mentioning the type of soil they covered, and
Rusinamhodzi et al. [2012, 2013] working on Lixisols and Luvisols in Mozambique).
Ncube et al. (2007) suggest improving current conditions by applying a series of
small doses of manure and fertilizers rather than a single application or double appli-
cations. Also, concentrating the little manure and fertilizer there is on fields near
