Nitrogen use efficiency by maize as affected by a mucuna short fallow and P application in the coastal savanna of West Africa uri icon

abstract

  • Maize is the primary food crop grown by farmers in the coastal savanna region of Togo and Benin on degraded (rhodic ferralsols), low in soil K-supplying capacity, and non-degraded (plinthic acrisols) soils. Agronomic trials were conducted during 1999-2002 in southern Togo on both soil types to investigate the impact of N and P fertilization and the introduction of a mucuna short fallow (MSF) on yield, indigenous N supply of the soil, N recovery fraction and internal efficiency of maize. In all plots, an annual basal dose of 100 kg K ha(-1) was applied to the maize crop. Maize and mucuna crop residues were incorporated into the soil during land preparation. Treatment yields were primarily below 80% of CERES-MAIZE simulated weather-defined maize yield potentials, indicating that nutrients were more limiting than weather conditions. On degraded soil (DS), maize yields increased from 0.4 t ha(-1) to 2.8 t ha(-1) from 1999 to 2001, without N or P application, in the absence of MSF, with annual K application and incorporation of maize crop residues. Application of N and P mineral fertilizer resulted in yield gains of 1-1.5 t ha(-1). With MSF, additional yield gains of between 0.5 and 1.0 t ha(-1) were obtained at low N application rates. N supply of the soil increased from 10 to 42 kg ha(-1) from 1999 to 2001 and to 58 kg N ha(-1) with MSF. Application of P resulted in significant improvements in N recovery fraction, and greatest gains were obtained with MSF and P application. MSF did not significantly affect internal N efficiency, which averaged 45 kg grain (kg N uptake)(-1). On non-degraded soils (NDS) and without N or P application, in the absence of MSF, maize yields were about 3 t ha-1 from 1999 to 2001, with N supply of the soil ranging from 55 to 110 kg N ha(-1). Application of 40 kg P ha(-1) alone resulted in significant maize yield gains of between 1.0 (1999) and 1.5 (2001) t ha(-1). Inclusion of MSF did not significantly improve maize yields and even reduced N recovery fraction as determined in the third cropping year (2001). Results illustrate the importance of site-specific integrated soil fertility management recommendations for the southern regions of Togo and Benin that consider indigenous soil nutrient-supplying capacity and yield potential. On DS, the main nutrients limiting maize growth were N and probably K. On NDS, nutrients limiting growth were mainly N and P. Even on DS rapid gains in productivity can be obtained, with MSF serving as a means to allow farmers with limited financial means to restore the fertility of such soils. MSF cannot be recommended on relatively fertile NDS.

publication date

  • 2005
  • 2005