Effect of conservation agriculture and integrated soil fertility management on urea nitrogen use efficiency

An experiment was carried out in a sub-humid and a semi-arid agro-ecologies in Kenya to evaluate the effects of conservation agriculture (CA) and/or Integrated Soil Fertility Management (ISFM) on maize (Z. mays) nitrogen use efficiency (NUE). Rain-fed maize crop was established under treatments including CA, ISFM, CA+ISFM and control. 15N labelled urea fertilizer and isotopic methods to determine grain NUE were used. Surprisingly, compared to CA and ISFM, NUE was lower under the combined practice (CA+ISFM), 19 and 15% in sub-humid and semi-arid, respectively. This could be attributed to microbial nitrogen immobilization aided by observed high water content under CA+ISFM.

Maize (Zea mays) production in Kenya is on the decline attributed to low soil fertility and erratic rainfall. Conservation Agriculture (CA) and Integrated Soil Fertility Management (ISFM) are renowned soil management practices that could address the above constraints (Sommer et al, 2018). When using mineral nitrogen (N) fertilizer in the said practices, it is important to investigate maize nitrogen use efficiency (NUE) under them.