Editing Sub-Saharan Africa (section)

=== Low productivity of subsistance farmers ===

Compared to South America and Asia, Sub-Saharan Africa has experienced persistently low crop yield productivity for more than 50 years.<ref>{{cite journal |title=Recent patterns of crop yield growth and stagnation |journal=Nature Communications |date=2012 |volume=3 |page=1293|doi=10.1038/ncomms2296 |pmid=23250423 |last1=Ray |first1=Deepak K. |last2=Ramankutty |first2=Navin |last3=Mueller |first3=Nathaniel D. |last4=West |first4=Paul C. |last5=Foley |first5=Jonathan A. |bibcode=2012NatCo...3.1293R }}</ref> As mentioned above, one factor influencing low productivity might be low access to credit studies. Many studies have focused on factors such as access to credit,<ref>{{cite journal |title=Time versus state in insurance: Experimental evidence from contract farming in Kenya. |journal=American Economic Review |date=2018 |volume=108 |issue=12 |pages=3778–3813|doi=10.1257/aer.20171526 |url=https://www.zora.uzh.ch/id/eprint/159985/1/Time_versus_State_Casaburi.pdf |last1=Casaburi |first1=Lorenzo |last2=Willis |first2=Jack }}</ref> and [[time preference]]s<ref>{{cite journal |title=Nudging farmers to use fertilizer: Theory and experimental evidence from Kenya. |journal=American Economic Review |date=2011 |volume=101 |issue=6 |pages=2350–2390|doi=10.1257/aer.101.6.2350 |url=http://www.nber.org/papers/w15131.pdf |last1=Duflo |first1=Esther |last2=Kremer |first2=Michael |last3=Robinson |first3=Jonathan }}</ref> as key explanations for low productivity of small farmers in Sub-Saharan Africa. However, recent studies have explored an alternative mechanism: quality of agricultural inputs.<ref>{{cite journal |title=re Ugandan farmers using the right quality inorganic fertilizers? |journal=Policy Brief: AGRA and the Ugandan Ministry of Agriculture. |date=2015 |url=https://elibrary.acbfpact.org/acbf/collect/acbf/index/assoc/HASH0151/7bc5e90f/6ea93be2/0406.dir/Uganda%20Farmers.pdf}}</ref> Indeed, usage of high-quality inputs, such as seeds and fertiliser, would substantially increase productivity of [[Subsistence agriculture|subsistance farmers]].<ref>{{cite journal |title=Ten striking facts about agricultural input use in Sub- Saharan Africa. |journal=Food Policy |date=2017 |volume=67 |pages=12–25|doi=10.1016/j.foodpol.2016.09.010 |pmid=28413243 |pmc=5384438 |last1=Sheahan |first1=Megan |last2=Barrett |first2=Christopher B. }}</ref> However, there is a small take up rate of this product by farmers, despite acknowledging their benefits.

==== Structure of the agricultural market ====

First, it is important to explain the structure of the agricultural input market in countries of the Sub-Saharan Africa. The majority of seeds and fertilizers are traded informally, often of uncertain quality, either exchanged between farmers or reused from previous harvests, in the case of seeds.<ref name="Lemon technologies and adoption: Me">{{cite journal |title=Lemon technologies and adoption: Measurement, theory, and evidence from agricultural markets in Uganda. |journal=Quarterly Journal of Economics |date=2017 |volume=132|issue=3 |pages=1055–1100 |doi=10.1093/qje/qjx009 |last1=Bold |first1=Tessa |last2=Kaizzi |first2=Kayuki C. |last3=Svensson |first3=Jakob |last4=Yanagizawa-Drott |first4=David }}</ref> Only a small number of farmers purchase inputs from the formal market, which is generally considered to offer higher-quality products. We can illustrate this with the example of the Nigerian stem market. Indeed, only 1% of the stems sold in the Nigerian market are certified, while the remaining 99% are traded informally—either as recycled stems from local varieties or as uncertified stems derived from previously improved varieties.<ref>{{cite journal  |title=Estimating seed demand in the presence of market frictions: Evidence from an auction experiment in Nigeria. |journal=Journal of Development Economics |date=2024 |volume=167 |page=103242|doi=10.1016/j.jdeveco.2023.103242 |pmid=38434593 |last1=Wossen |first1=T. |last2=Spielman |first2=D. J. |last3=Alene |first3=A. D. |last4=Abdoulaye |first4=T. |pmc=10831485 }}</ref>

==== Uncertainty about quality of agricultural inputs ====

Recent studies explain that farmers mistrust the quality of fertilisers and seeds sold in the formal market.<ref name="Lemon technologies and adoption: Me"/> The study realized in Uganda<ref name="Lemon technologies and adoption: Me"/> infers quality across fertilizer and hybrid seeds varies significantly due to adulteration: sellers tend to mix the fertilizer with poor soil. However, one study realized in Tanzania<ref>{{cite journal   |title=Misperceived quality: Fertilizer in Tanzania. |journal=Journal of Development Economics |date=2021 |volume=148|doi=10.1016/j.jdeveco.2020.102579 |url=https://figshare.com/articles/journal_contribution/23478044 |last1=Michelson |first1=Hope |last2=Fairbairn |first2=Anna |last3=Ellison |first3=Brenna |last4=Maertens |first4=Annemie |last5=Manyong |first5=Victor }}</ref> finds no adulteration in agricultural inputs, but do find that visual appearance of input sold in the formal market is degraded. Whether one study or the other is correct, both papers highlight uncertainty about fertilizer's quality, thus generating mistrust among farmers and consequently generates a low take-up rate.

Another factor highlighting uncertainty about quality is the presence of relatively homogenous pricing among different quality of the same inputs.<ref>{{cite journal  |title=Misperceived quality: Fertilizer in Tanzania. |journal=Journal of Development Economics |date=2021 |volume=148|doi=10.1016/j.jdeveco.2020.102579 |url=https://figshare.com/articles/journal_contribution/23478044 |last1=Michelson |first1=Hope |last2=Fairbairn |first2=Anna |last3=Ellison |first3=Brenna |last4=Maertens |first4=Annemie |last5=Manyong |first5=Victor }}</ref> While in most markets price is a good indicator of quality.<ref>{{cite journal  |title=Price as an indicator of quality: Report on an enquiry |journal=Economica |series=New Series |date=1966 |volume=33 |issue=129 |jstor=2552272 |url=https://www.jstor.org/stable/2552272 |last1=Gabor |first1=André |last2=Granger |first2=C. W. J. |pages=43–70 |doi=10.2307/2552272 }}</ref> the higher the quality, the higher the price- , in this case, uniform pricing prevents farmers from using price as a signal of input quality. Consequently, the inability of farmers to infer the quality, either through physical appearance or price, creates [[Information asymmetry|asymmetric information]] in the market, leading an inefficient market.<ref name="Lemon technologies and adoption: Me"/>

Some papers have tried to understand why sellers do not simply charge higher prices when they offer high-quality seeds and fertilizers,<ref name="Lemon technologies and adoption: Me"/> using a [[Bayesian inference|Bayesian learning model]].<ref>{{cite journal |last1=Jovanovic |first1=B. |last2=Nyarko |first2=Y. |title=A Bayesian learning model fitted to a variety of empirical learning curves |journal=Brookings Papers on Economic Activity: Microeconomics |date=1995 |pages=247–305 |doi=10.2307/2534775 |jstor=2534775|url=https://www.brookings.edu/wp-content/uploads/1995/01/1995_bpeamicro_jovanovic.pdf }}</ref> It is challenging for a company to sell high-quality inputs at a [[Premium pricing|premium price]] and build a reputation in the long term, meaning that farmers will trust the seller regarding the quality of its products. Indeed, as farmers are highly suspicious -due to fear of being scammed- their [[willingness to pay]] for high-quality products is very low. So even if the firm sells high-quality products, it will take too long for farmers to start trusting the firm, and for the seller to become profitable.<ref name="Estimating seed demand in the prese">{{cite journal |title=Estimating seed demand in the presence of market frictions: Evidence from an auction experiment in Nigeria. |journal=Journal of Development Economics |date=2024 |volume=167 |page=103242|doi=10.1016/j.jdeveco.2023.103242 |last1=Wossen |first1=Tesfamicheal |last2=Spielman |first2=David J. |last3=Alene |first3=Arega D. |last4=Abdoulaye |first4=Tahirou |pmid=38434593 |pmc=10831485 }}</ref>

==== Policy recommendation ====
The literature advises to actually improve farmers perception of true quality itself, and not to improve the quality of the products which already meet the standards.<ref name="Estimating seed demand in the prese"/> This can be done by providing more information about inputs quality, how they should look like, where they come from, making firms more reliable.<ref name="Estimating seed demand in the prese"/> That would allow more companies to enter the market and sell formally higher inputs, instead of farmers using their own seed or using seed of unknown quality bought in informal markets.