Research article Maize yield as affected by the interaction of fertilizer nitrogen and phosphorus in the Guinea savanna of Nigeria Abdullahi Ibrahim Tofa a, * , Alpha Yaya Kamara a , Bashir Ahmad Babaji b , Kamaluddin Tijjani Aliyu a , Temitope Damian Ademulegun a , Jenneh Fatima Bebeley a, c a International Institute of Tropical Agriculture (IITA), P.M.B. 5320, Oyo Rd., Ibadan, 200211, Nigeria b Department of Agronomy, Ahmadu Bello University, P.M.B. 1045, Zaria, 810222, Nigeria c Centre for Dryland Agriculture, Bayero University, Kano, 700241, Nigeria ARTICLE INFO Keywords: Nitrogen Phosphorus N  P interaction Yield N use efficiency ABSTRACT The soils of the Nigeria savannas are particularly low in nitrogen (N) and phosphorus (P) and negatively affects maize productivity. The main objective of the study was to evaluate the interactive effect of N and P fertilizers on maize growth, grain yield, nitrogen uptake and N use efficiency. Field experiments were conducted during the 2015 and 2016 cropping seasons at Iburu in southern Guinea and Zaria in northern Guinea savanna zones of Nigeria. The treatments consisted of three levels of nitrogen (0, 60, and 120 kg N ha 1 ) and three levels of phosphorus (0, 13, and 26 kg P ha 1 ). The experimental design consisted of three replications in a split-plot design, with N as the main plot and P as the subplot. Our results show that the response of maize to N de- pends on the application of P. Higher yields were obtained with the combined application of 120 kg N ha 1 and 26 kg P ha 1 in both locations. With no P applied, plant N uptake (PNU) was greater at N rate of 120 kg ha 1 at Iburu while in Zaria, it increases with increase in N from 0 to 60 kg ha 1 . When P was applied at 13 kg ha 1 , the PNU increased by 52 and 66% at Iburu while in Zaria the increases were 51 and 57% each with N application of 60 and 120 kg ha 1 , respectively, compared with zero N rate. The values for N recovery efficiency (NRE) and agronomic efficiency (AE) were lower for N rate of 120 than for 60 kg ha 1 irrespective of P application rate at both locations. The N utilization efficiency (NUTE) however was higher at 120 N kg ha 1 under 26 kg P ha 1 across locations. It can be concluded from these results that in low fertile soils environments such as the Nigeria savannas, N fertilizer should be applied along with P fertilizer for optimum growth, grain yield and ni- trogen use efficiency of maize. 1. Introduction Maize (Zea mays L.) is an important crop in the Guinea savanna zone of Nigeria but mean grain yield is less than 2 t ha 1 due to numerous biotic, abiotic and management constraints [1, 2]. Among several abiotic constraints, inherently low N and available P in the soils have been re- ported to limit maize yield in the area [3, 4]. Savanna soils are mostly kaolinitic Alfisols with minimal organic matter and cation exchange ca- pacity [5]. The N deficiency has been identified as the major limiting factor for maize productivity in savanna environments [5]. Land usage is becoming more intensive as a result of rising population pressure. The continual usage of the lands has resulted in nutrient and organic matter depletion in the soil, limiting soil productivity and agricultural produc- tion. The annual loss of maize yield due to N stress has been reported to range between 10 and 50% [4]. Nitrogen deficiency in Nigeria savannas is caused by a variety of factors, including runoff and leaching of soil N below the root zone as a result of excessive rains [6], poor weed man- agement in farmers' fields [7, 8, 9] and the use of sub-optimal quantities of inorganic fertilizer due to high pricing [10] and non-availability of fertilizer. After nitrogen, phosphorus is the second most limiting plant nutrient in crop production in most agricultural soils in the Guinea savanna (GS) of Nigeria [11]. A study by Shehu et al. [12] showed very low P levels (less than 3 mg kg 1 ) in most soils in northern Nigeria's savanna. Another study found that P levels were 7 mg kg 1 or lower in 93% of study sites in the Sudan savanna and 92% in the northern GS of Nigeria [13]. Ac- cording to Ekeleme et al. [2] 80% of fields in Nigerian savannas had P levels that were either low or very low. * Corresponding author. E-mail address: a.tofa@cgiar.org (A.I. Tofa). Contents lists available at ScienceDirect Heliyon journal homepage: www.cell.com/heliyon https://doi.org/10.1016/j.heliyon.2022.e11587 Received 19 November 2021; Received in revised form 23 March 2022; Accepted 7 November 2022 2405-8440/© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Heliyon 8 (2022) e11587