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These analyses did show some changes in rainfall and dry spells which accorded with farmers’ perceptions, although most of these were not significant enough to provide the farmers with scientific proof thereof. Several studies, wherein there was no clear evidence in rainfall patterns to support the farmers’ concerns, explained these perceived changes in rainfall as being the result of changes in other physical parameters (Dahlberg and Blaikie, 1996; Kinlund, 1996; Ovuka and Lindqvist, 2000; Stroosnijder, 2007). Biophysical factors other than rainfall deficiency influence water availability for a crop and can contribute to farmers’ increased concerns about rainfall (Lindskog and Tengberg, 1994; Dahlberg and Blaikie, 1996; Amsalu et al., 2007; Slegers and Stroosnijder, 2008). In both study areas, the farmers believed that deforestation had contributed to their problems (cf. Meze-Hausken, 2004) and that different properties of a soil influence a plant’s ability to withstand dry conditions. Deeper insight is needed into local biophysical processes which interact with soil-water properties, since this will contribute to a better understanding of farmers’

concerns about the rains.

Chapter 6

Comparison of farmers’ perceptions of drought with moisture and nutrient availability to maize in semi-arid central

Tanzania

6. Comparison of farmers’ perceptions of drought with moisture and nutrient availability to maize in semi-arid central Tanzania

Abstract

Since there is no unequivocal proof of an increased problem of meteorological drought, this chapter looked beyond meteorological data by comparing farmers’ knowledge about spatial differences in drought susceptibility of crops with moisture and nutrient availability to maize during the 2005/06 cropping season. With help of farmers suitable fields were selected of the three soil types distinguished by farmers, Dark, Red and Pale. Farmers were provided with the same maize variety, Kilima. The experimental design was a 2² factorial with manure and water conservation as factors, each at two levels (with or without). The fields studied were managed by the farmers themselves and according to their usual practice.

Rainfall, soil moisture, soil, and crop data were analyzed using a water balance model and QUEFTS, a model to evaluate soil fertility. Yield assessments of both analyses and by farmers were compared. The plots where manure was applied showed better crop growth than the other plots of the same soil type. Effects of the ridges, however, were limited, but might have been significant if a period of more severe moisture stress would have occurred during this particular cropping season. Farmers’ knowledge about spatial differences in drought susceptibility of crops generally agreed with the outcomes of the analyzed data.

Farmers perceived that in good rainfall years, the less sandy soils perform relatively best due higher fertility status, while in a bad rainfall year lighter soils are relatively most productive because of easier water infiltration and lower water demands. Chemical and physical properties of the Dark soil were best, and those of the Red soil were poorest. Yield assessments by farmers were low compared to QUEFTS calculated yields and yield estimates based on the water balance model. These deviances might be attributed to moisture stress during periods when soil moisture is near permanent wilting point and is not readily available to the crop. Farmers distinguished meteorological drought from local manifestations of soil nutrient deficiency, or moisture deficiency and recognized that natural conditions of a soil as well as their activities influence nutrient and soil moisture availabilities.

6.1. Introduction

6.1.1. Perceptions of drought

A Goal set by the 1996 World Food Summit was to reduce by half the number of malnourished people by 2015 (FAO, 2006). The biggest challenge is to achieve this goal in

sub-Saharan Africa (SSA), where a third of the fast-growing population is food insecure (FAO, 2006). Over the past 40 years, average food production per capita has declined (Love et al., 2006). Since most people in SSA live in rural areas where subsistence agriculture is the major economic activity, development approaches should prioritize improvement of agricultural productivity in a sustainable manner.

One limitation for the achievement of sustainable agriculture in semi-arid East Africa is the existing mismatch between problem perceptions of scientists and local land users.

Scientists consider soil degradation as major limitation for sustainable production, while farmers mostly relate reduced productivity to drought. From the perspective of the conservation of natural resources in Africa it is of importance that the production-reducing obstacle ‘drought’ is taken into serious consideration.

Causes of drought can be more complex than shortage of rainfall (Rockström, 2003b).

Biophysical factors other than lack of rain influence soil-water availability and can contribute to farmers’ increased concerns about rainfall (Lindskog and Tengberg, 1994;

Dahlberg and Blaikie, 1996). Amsalu (2007) found a discrepancy between farmers, who perceived that rainfall had become more unreliable, and the rainfall data, which showed an improvement in terms of amount and distribution. Amsalu suggests that water loss due to soil erosion and increased water needs due to population growth could possibly explain this discrepancy. Thurrow and Taylor (1999) refer to this “drought paradox” as some form of agricultural drought and attribute it to degradation of vegetation and to processes of soil erosion and soil crusting. Others have drawn similar conclusions (Rietkerk and Van de Koppel, 1997; Stocking and Murnaghan, 2001; Stroosnijder, 2008).

Rietkerk (1998) claims that soil-water and nutrient availability are decreasing through soil degradation processes. Such processes increase the susceptibility of crops to drought.

Farmers relate these processes rarely directly to soil degradation, but may perceive adverse effects on crop yield as the result of meteorological drought (Stocking and Murnaghan, 2001).

Slegers and Stroosnijder (2008) developed an agricultural drought framework (ADF)¹ that takes into account soil moisture deficiency as well as nutrient deficiency as possible factors influencing farmers’ growing concerns about drought and that therewith accommodates scientists' as well as farmers' concerns about major agricultural productivity-reducing problems (Slegers and Stroosnijder, 2008).

1 The ADF and its drought components were developed based on empirical insights into the inter-relation between drought, land degradation and biological productivity from the perspectives of farmers. These drought components are termed: “meteorological drought”, “soil water drought” and “soil nutrient drought” to refer to rainfall deficiency, soil moisture deficiency and nutrient deficiency, respectively. Since these drought components were developed from the perspective of farmers, they do not necessarily reflect the views or concepts applied by physical scientists.

6.1.2. Drought in Goima, Tanzania

In the period from mid December 2005 to June 2006, a study was performed in two villages, Goima and Mirambu villages², located within Goima Ward. A sociological study had preceded the biophysical study, in which the central question was how farmers perceive drought (Slegers, 2008a).

A general statement among farmers in Goima is that “if only it would rain, our harvests will be good”. Farmers firmly stated that they had never personally experienced a drought, which may appear as a paradox in this drought-stricken region. The reason is that they adhere to the principle that drought would imply complete crop failure due to absence of rainfall, the land being bare and dry. In less severe situations, in a year with reduced crop production due to deficient rainfall or when “rainfall and sunshine are out of balance”

farmers prefer to talk about a bad year (mwaka mbaya) or about a scorching sun (jua kali) instead of drought (ukame) (Slegers, 2008b). However, they often hear the word drought being used on the radio and by local agricultural services during what they refer to as bad years.

The farmers in Goima feel that rainfall has become less predictable during the past ten to twenty years, especially early in the season. They are concerned about increased frequency, but even more so about increased severity of bad years. Farmers believe that trees bring rainfall and that the ongoing deforestation has increased the drought problem over the past two decades (cf. Meze-Hausken, 2004; Slegers et al., 2005).

The seasonal and monthly rainfall of the past 36 seasons (1970/71-2005/06), the mean rainfall per rainy day, the number of rainy days in a season, the maximum daily rainfall and length of dry spells were analyzed for possible trends (Slegers, 2008a). These analyses did only show some changes which accorded with farmers’ perception. Only the mean dry spell length in December, which is at the start of the cropping season, indicated a significant increase (P < 0.01). Other changes were insignificant and could not provide farmers with further scientific proof of perceived changes.

Farmers understand that their vulnerability to drought is diverse and depends on characteristics and state of their land and on their land management practices (Slegers, 2008b). Based on this knowledge, an experiment was set up on the three soil types that farmers distinguish. Meteorological, soil, manure and crop data were used to assess the vulnerability of maize to water and nutrient stress. Maize (Zea Mays) was used as test crop since it is most commonly grown by farmers because of its marketability. The outcomes of the analyses were compared with farmers’ knowledge about their soils and effects of land management practices on the crop’s performance.

This chapter looks beyond meteorological data to address the ‘drought’ problem as perceived by farmers in Goima Ward. The objective was to understand the source of farmers’ growing concerns about the rains by comparing their knowledge about spatial differences in drought vulnerability of crops with moisture and nutrient availability to maize during the 2005/06 cropping season.

2 When referring to both villages, Goima will be mentioned