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

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 À1 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 À1 to 2.8 t ha À1 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 À1 . With MSF, additional yield gains of between 0.5 and 1.0 t ha À1 were obtained at low N application rates. N supply of the soil increased from 10 to 42 kg ha À1 from 1999 to 2001 and to 58 kg N ha À1 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) À1 . On non-degraded soils (NDS) and without N or P application, in the absence of MSF, maize yields were about 3 t ha À1 from 1999 to 2001, with N supply of the soil ranging from 55 to 110 kg N ha À1 . Application of 40 kg P ha À1 alone resulted in significant maize yield gains of between 1.0 (1999) and 1.5 (2001) t ha À1 . 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.

The effects of herbivory and nutrients on plant biomass and carbon storage in Vertisols of an East African savanna

“…We observed lower apparent N recovery compared to an average of 21-27% when N was added alone and 36-45% when N and P were added together in maize farm in coastal savanna of West Africa (Fofana et al, 2005). In addition, Fofana et al (2005) indicated that addition of N and P together significantly improved the apparent N uptake compared to adding N alone, which was not the case in this study. We broadcasted the fertilizer without manually mixing it with the soils.…”

Nitrogen and phosphorus capture and recovery efficiencies, and crop responses to a range of soil fertility management strategies in sub-Saharan Africa

“…Averaged over three seasons at sole 100 kg ha -1 N application, NCE was significantly higher on infields compared to outfields (0.52 vs. 0.38 kg kg -1 ). In a related experiment on degraded and non-degraded soils in Togo, Fofana et al (2005) also demonstrated that NCE was always superior on a non-degraded soil. Significant improvements in the NRE of applied N and overall NCE on the degraded soil was only realized when N and P were simultaneously applied.…”

Assessment of nutrient deficiencies in maize in nutrient omission trials and long-term field experiments in the West African Savanna

“…Increases in the yield of cereal crops following the cultivation of legumes relative to those obtained with continuous cereal cropping have been frequently reported in the Guinea savannah (Muhr et al 1999b;Alvey et al 2001;Franke et al 2004;Fofana et al 2005). Often the amount of N and sometimes phosphorus (P) available to cereals improves in legume-cereal rotations.…”