# **_2.1. Fertilizer_**

In an environment where initial soil productivity may be low and/or where crops are cultivated without the ability to leave plots fallow, replenishing the soil is essential for the long term viability of agriculture (Henao and Baanante 2006). Fertilizer functions as a yield sustaining and enhancing input by adding nutrients required for plant growth to the soil. Several researchers have estimated that over 50 percent of productivity gains experienced during the Green Revolution in Asia can be attributed to increased use of inorganic fertilizer alone (Hopper 1993; Tomich, Kilby, Johnston 1995). Fertilizer can be both organic (e.g., manure and compost) and inorganic (often described as “chemical” or “mineral”), which function best as complements (Weight and Kelly 1999), a practice encouraged by proponents of integrated soil fertility management (Place et al. 2003). Organic and inorganic fertilizers provide specific benefits and, therefore, do not make perfect substitutes. Moreover, Morris et al. (2007) claim that simply not enough organic matter exists to “fix” the soil nutrient deficiency issues in SSA.

Using FAOSTAT data from 2009, Minot and Benson (2009) find that SSA households apply an average 13 kilograms of inorganic fertilizer per hectare of cultivated land, a statistic that has proliferated and prompted considerable pressure within African governments to stimulate fertilizer use, perhaps most prominently within CAADP policy dialogues. While these continentlevel statistics have fueled the debate on low fertilizer use, variation across countries is recognized. For example, when grouping countries by intensity of application, Morris et al. (2007) found that only Malawi (from the list of LSMS-ISA countries) fell into the high intensity category where more than 25 kilograms per hectare are applied on average. Organic fertilizer use rates are far more difficult to come by at the national level since there is often not a market for compost or manure. Household surveys, like those utilized in this study, are essentially the only method of tabulating the incidence of organic fertilizer use.

Table 1: Average kilograms of fertilizer applied per hectare of cultivated land

|||FAOST<br>(2010 d|AT<sup>~~1~~</sup><br>ata)||World Bank<br>(2009 data)<sup>2</sup>||Literature review from<br>household surveys<sup>3</sup>|
|---|---|---|---|---|---|---|---|
||Nitrogen<br>(N)|Phosphate<br>(P205)|Potash<br>(K20)|Total<br>nutrients|Total<br>nutrients|Total|Source|
|Ethiopia|10.4|10.8|0.0|21.2|17.7|17|Spielman et al. (2011)|
|Malawi|23.1|4.5|4.3|31.9|28.5|55.7*|Ricker-Gilbert et al. (2009)|
|Niger|0.3|0.1|0.1|0.5|0.4|-|-|
|Nigeria|2.0|0.3|0.3|2.6|2.1|-|-|
|Tanzania|4.4|0.6|0.7|5.7|8.7|-|-|
|Uganda|0.7|0.3|0.3|1.3|2.1|2.4*|Matsumoto and Yamano(2011)|
|_SSA Average_|_6.5_|_2.9_|_1.6_|_11.0_||||
|_LDC Average_|_11.2_|_2.8_|_1.3_|_15.3_||||

Sources:<sup>~~1~~</sup> FAOSTAT. Cultivated land defined as arable land plus land under permanent crop. See more details at FAOSTAT. Sub-Saharan African estimates come from an aggregation of eastern, western, southern, and middle Africa (32 countries), per the regional breakdown on FAOSTAT.<sup>2</sup> World Bank. World Development Indicators. 3From review of literature. Only nationally or near nationally representative studies with unconditional fertilizer application rates included in this table. See Appendix 1 for other studies and details. *Not specific to nutrient content.

While major household surveys and complementary analysis on fertilizer use exists in certain Sub-Saharan countries, cross-country studies at the same level are far more difficult to come by. As such, our best means of comparing fertilizer use rates across countries is to rely on macro3