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E, Ellis J, Rhodes JD (eds) Methods of soil analysis. Part 2. Chemical and Microbiological
Properties, 2nd edn. Agronomy Monograph 9.2. ASA and SSSA, Madison, WI. pp 159–166
Trewavas AJ (2001) The population/biodiversity paradox. Agricultural efficiency to save wilderness. Plant Physiol 125:174–179
Tuomisto HL, Hodge ID, Riordan P, Macdonald DW (2012) Does organic farming reduce environmental impacts? – a meta-analysis of European research. J Environ Manag 112:309–320
URT (2017) Simiyu investment guide. United Republic of Tanzania (URT). Retrieved from http://
esrf.or.tz/docs/guide-simiyu.pdf on 11 Aug 2019
Wickham H (2016) ggplot2: elegant graphics for data analysis. Springer, New York
T. N. Bwana et al.
Thomas GW (1982) Exchangeable cations. In: Page AL, Miller RH, Keeney DR, Baker DE, Roscoe
E, Ellis J, Rhodes JD (eds) Methods of soil analysis. Part 2. Chemical and Microbiological
Properties, 2nd edn. Agronomy Monograph 9.2. ASA and SSSA, Madison, WI. pp 159–166
Trewavas AJ (2001) The population/biodiversity paradox. Agricultural efficiency to save wilderness. Plant Physiol 125:174–179
Tuomisto HL, Hodge ID, Riordan P, Macdonald DW (2012) Does organic farming reduce environmental impacts? – a meta-analysis of European research. J Environ Manag 112:309–320
URT (2017) Simiyu investment guide. United Republic of Tanzania (URT). Retrieved from http://
esrf.or.tz/docs/guide-simiyu.pdf on 11 Aug 2019
Wickham H (2016) ggplot2: elegant graphics for data analysis. Springer, New York
T. N. Bwana et al.