Appendix Table S1. Studies included in this meta-analysis and the variables available for analysis

No / Author(year) / Source / Country / Variables
1 / Abunyewa et al (2007) / JAgron 6: 302–309 / Ghana / N, P, K, C, MY
2 / Ademba et al. (2015) / East AfrAgric For J 81: 1–11 / Kenya / N, P, K, C, Ca, Mg, MY
3 / Admas et al. (2015) / Amer J Plant NutrFert 5: 1-15 / Ethiopia / N, P, C, S, MY
4 / Akongwubel et al. (2012) / Int J Agric For 2: 138-144 / Nigeria / N, P, K, C, Ca, Mg, MY
5 / Amujoyegbe et al. (2007) / Afr J Biotech6: 1869-1873 / Nigeria / N, P, K, MY
6 / Arbab& Mubarak (2016) / AgricSci Digest36: 44–47 / Sudan / N, K, K, C, Ca, Mg
7 / AyoolaAdeniyan (2006) / Afr J Biotech5: 1386-1392 / Nigeria / N, P, K, Ca, Mg, MY
8 / Bakayoko et al. (2009) / Afr J EnvirSci Tech3: 190-197 / Côte d'Ivoire / N, P, K, C
9 / Boateng et al. (2006) / West Afr J Appl Ecol. 9: 1-11 / Ghana / N, P, K, C, Ca, Mg, MY
10 / Chikowo et al. (1999) / Afr Crop Sci J383–395 / Zimbabwe / N, P, K, C, Ca, Mg
11 / Chirinda et al. (2003) / Afr Crop Sci Proc 6: 454–463 / Zimbabwe / N, P, K, C, Ca, Mg
12 / Chivenge et al. (2009) / Agron J101:1266–1275 / Kenya / N, P, K, MY
13 / Daudu et al. (2006) / J Agron 5: 220-227 / Nigeria / N, P, K, C, Ca, Mg
14 / Delve et al. (2001) / AgricEcosys Environ84: 227–243 / Kenya / N, C, LL
15 / Esse et al. (2001) / AgricEcosys Environ 83: 55–63 / Niger / N, P, K
16 / Falconnier et al. (2015) / Field Crops Res 187: 113–126 / Mali / N, P, K, C, MY
17 / Fatondji et al (2009) / NutrCyclAgrEcosys85:225–239 / Niger / N, P, K, C
18 / Gonda (2015) / PhD Thesis / Niger / N, P, K, C, Ca, Mg
19 / Hoffmann et al. (2001) / AgricEcosys Environ 86: 263–275 / Nigeria / N, P, K, C
20 / Jackson &Mtengeti (2005) / Livestock Res Rural Dev 17: Online / Tanzania / N, P, K, C
21 / Kato et al. (2014) / SustAgric Res 3: 50–55 / Uganda / N
22 / KituaMrema (2003) / Tanzania J Agric 6: 39–44 / Tanzania / N, P, K, C, Ca
23 / Lekasi et al. (2001) / HDRA publication / Kenya / N, P, K, C
24 / Mafongoya et al. (2000) / BiolFertil Soils 30:298–305 / Zimbabwe / N, P, C
25 / Maman et al. (2013) / Afr J Plant Sci7: 162-169
/ Niger / N, P, K, Ca, Mg
26 / Masaka et al. (2013) / NutrCyclAgroecosyst 96: 149-170 / Zimbabwe / N, C
27 / MataraukaSamaz (2014) / Int J Manure Fert3: 489-494
/ Zimbabwe / N, P, K, C
28 / Mavengahama Mapanda (2012) / Afr J Agric Res 7: 4362–4367 / Zimbabwe / N, P, K,Ca, Mg
29 / McClintock &Diop (2005) / Intl J Agric Sustain 3: 79-91 / Senegal / N, P, K, C, S, Ca, Mg
30 / Meerere et al (2001) / Afr J Sci Tech 1: 14-21 / Tanzania / N, P, C
31 / Mlowe (2009) / MSc thesis / Tanzania / N, P, K, C, Ca, Mg
32 / Mtambanengwe et al. (2006) / NutrCyclAgroecosyst76:271–284 / Zimbabwe / N, C, MY
33 / Muambole (2014) / MSc thesis / Mozambique / N, P, K, C
34 / Mubenderi et al. (1999) / Afr Crop Sci J 7: 407–413 / Zimbabwe / N, P, K, C, Ca, Mg
35 / Mucheru et al. (2007) / AgroforSyst 69:189–197 / Kenya / N, P, K, Ca, Mg, MY
36 / Mugwe et al. (2009) / ExpAgric45: 47–59 / Kenya / N, P, K, Ca, Mg, MY
37 / Muhereza et al. (2014) / J Agric Environ Int Dev 108: 135-151 / Uganda / N, P, K, Ca, Mg
38 / Munyabarenzi (2014) / MSc thesis / Rwanda / N, P, MY
39 / Murwira et al. (1998) / Soil Fert Net / Zimbabwe / N
40 / Ncube et al. (2007) / NutrCyclAgroecosyst77: 53-67 / Zimbabwe / N, P, C, MY
41 / Negassa et al. (2001) / 7th East &Southern Africa / Ethiopia / N, P, N:P, MY
42 / Nhamo et al. (2004) / Managing Nutrient cycles (book) / Zimbabwe / N, K, C, Ca, Mg
43 / Nyambati (2002) / PhD Thesis / Kenya / N, P, K, C, Ca, Mg
44 / Ojo et al (2015) / IntSchol Res Notices / Nigeria / N, P, K, C, S, Ca, Mg, MY
45 / Okalebo et al. (2003) / AFNET publication / Kenya / N, P, K
46 / Okoko et al (2003) / East AfrAgric For J 69: 89-98 / Kenya / N, P, K, C, S, Ca, Mg, MY
47 / Olal (2015) / MSc thesis / Kenya / N, P
48 / Onduru et al. (1999) / Managing Africa’s Soils (book) / Kenya / N, P, K
49 / Onduru et al. (2008) / Int J Agric Res 3: 166–187 / Kenya / N, P, K
50 / Onwonga et al. (2013) / Amer J Agric Res 3: 939-958 / Kenya / N, P, K, C, S, Ca, Mg
51 / Opala et al. (2015) / J Agric Rural Dev Trop 116: 1–9 / Kenya / N, P, K, MY
52 / Otinga et al. (2013) / Field Crops Res 140: 32–43 / Kenya / N, P, K, C, S, Ca, Mg, MY
53 / Oyewole et al. (2014) / J IntSci Pub 2: 1314-8591 / Nigeria / N, P, K
54 / Pincus et al (2016) / AgricEcosys Environ 225: 62–71 / Uganda / N, P, K, C
55 / Powell et al. (1996) / AgricSyst / Senegal / N, P, K
56 / Snijders et al. (1992) / KARI report / Kenya / N, P, K, C
57 / Tadesse et al (2013) / Amer J Res Comm / Ethiopia / N, P, K, C
58 / Tanimu et al. (2013) / J AgricSci 5: 226-234 / Nigeria / N, P, K, MY
59 / Tittonell et al. (2010) / Plant Soil 328:253–269 / Kenya / N, P, K, C
60 / Vanlauwe et al. (2001) / Agron J / Nigeria / N, P, K, C, Ca, Mg
61 / Wanjekeche et al. (1999) / Proceeding / Kenya / N, P, K, C, Ca, Mg
62 / Wapa et al (2014) / J Agric Environ Sci 3: 299–314 / Nigeria / N, P, K, C, MY
63 / WutaNamugafata (2012) / Afr J Agric Res 7: 3853–3859 / Zimbabwe / N, P, K, C
64 / Zingore et al (2012) / NutrCyclAgroecosys / Zimbabwe / N, P, K, C, Ca, Mg, MY

C = carbon; Ca = calcium; K = potassium; Mg = magnesium; N = nitrogen; P = phosphorus; S = sulphur; MY = maize grain yield

References (not listed in main reference)

Esse PC, Buerkert A, Hiernaux P, Assa A (2001). Decomposition of and nutrient release from ruminant manure on acid sandy soils in the Sahelian zone of Niger, West Africa.AgricEcosys Environ 83: 55–63.

Falconnier GN, Descheemaeker K, Van Mourik TA, Giller KE (2016) Unravelling the causes of variability in crop yields and treatment responses for better tailoring of options for sustainable intensification in southern Mali. Field Crops Res 187: 113-126.

Kitua MJK, Mrema JP (2003) Effect ofMinjingu phosphate rock (MPR) and farm yard manure (FYM) applied to an OxicHaplusults on Bray-l-P and the response of maize toapplied MPR and FYM. Tanzania J AgrSci 6: 39–44.

Lekasi JK, Tanner JC, Kimani SK, Harris PJC (2001) Manure management in the Kenya highlands: Practices and potential, 2nd edition. Emmersons, Kenilworth, UK. 35pp.

Ncube B, Dimes JP, Twomlow SJ, Mupangwa W, Giller KE (2007) Raising the productivity of smallholder farms undersemi-arid conditions by use of small doses of manureand nitrogen: a case of participatory research. NutrCyclAgroecosyst77: 53-67.

Nyambati EM (2002) Management and nutritive evaluation of Mucunapruriensand Lablab purpureus– maize intercrops in the sub-humid highlands of Northwestern Kenya. Ph.D. Dissertation, University of Florida.

Snijders, P.J.M., Orodho, A.B., Wouters, A.P. (1992) Effect of manure application methods on yield and quality of Napier grass. Kenya Agricultural Research Institute, Naivasha, Kenya,pp 50.

Tanimu J (2012) Effect of cowdung management and urea fertilizer on some soil chemical properties and maize (Zea mays l.) yield in the northern guinea savanna of Nigeria.PhD Thesis, Ahmadu Bello University, Nigeria.

Wanjekeche E, MwangiT, PowonP, KhaembaJ (1999) Survey of management practices of manure and its nutrients in west Pokot district of Kenya. pp 355-359, In: J.S. Tenywa, J.Y.K. Zake, P. Ebanyat, O. Semalulu, S.T. Nkalubo (eds.). Soil Science A Key to Sustainable Land Use. Proceedings of the 17th Conference, 6-10 September 1999 Kampala, Uganda, SSSEA and Makerere University, Kampala Uganda.