Maize (Zea mays L.) Response to Secondary and Micronutrients for Profitable N, P and K Fertilizer Use in Poorly Responsive Soils

Abstract

Deficiencies of secondary and micronutrients (SMNs) are major causes of low maize yields in poorly responsive soils. This phenomenon minimizes the agronomic efficiency of N, P and K fertilizers and consequently result in a dwindling economic benefit associated with their use. Therefore, 18 on-farm trials were conducted in western Kenya during two cropping seasons to assess maize response to three NPK amendments; (i) N, P, K, Ca, Zn and Cu (inorganic and organic); (ii) N, P, K, Ca, Zn and Cu (inorganic) and (iii) N, P K, Zn and Cu (inorganic) and evaluate the profitability of their use compared to additions of only N, P and K fertilizers. In this set of experiments, maize response to any amendment refers to a yield increase of ≥2 t ha −1 above control and could be categorized in three clusters. Cluster 1, comprising of nine sites, maize responded to all amendments. Cluster 2, holding six sites, maize responded only to one amendment, N, P, K, Ca, Zn and Cu (inorganic). In this cluster, (2), emerging S, Mg and Cu deficiencies may still limit maize production. Cluster 3; consisting of three sites, maize responded poorly to all amendments due to relatively high soil fertility (≥17 mg P kg −1). Profitability of using NPK amendments is limited to Cluster 1 and 2 and the largest Value Cost Ratio (VCR) of 3.1 is attainable only when soil available P is below 4.72 mg kg −1. These variable responses indicate the need for developing site-specific fertilizer recommendations for improved maize production and profitability of fertilizer use in poorly responsive soils.

Fertilizer profitability for smallholder maize farmers in Tanzania: A spatially-explicit ex ante analysis

“…This paper has illustrated a simple yet useful method of predicting yield responses to fertilizer over heterogeneous production landscapes, with a view toward guiding strategic investments and policy interventions. In our case study of smallholder Tanzanian maize farmers, our results indicate highly variable fertilizer responses over geographic space, in line with other empirical studies in the region (e.g., [4][5][6][7]). While fertilizer use is profitable, on average, it is not profitable everywhere.…”

“…Why are fertilizer usage levels so low? A rich empirical literature has developed in recent years, which emphasizes three key constraints:-agronomic responses to fertilizer are often much lower in farmers' fields than on researcher-managed trials, and such responses are substantially variable over geographic space [4][5][6][7][8]. Low and variable agronomic returns translate into low and variable economic returns once considering the local farm-gate crop and fertilizer prices.…”

Assessing and understanding non-responsiveness of maize and soybean to fertilizer applications in African smallholder farms

“…Farm fields where no satisfactory gains in crop productivity are achieved by standard fertilizer applications have been referred to as ‘non-responsive’ ( Vanlauwe et al, 2010 ), and pose major risks to investments ( Liverpool-Tassie et al, 2017 ), and the environment ( Albanito et al, 2017 ; Russo et al, 2017 ). Few studies have systematically investigated the occurrence of fertilizer non-responsiveness in maize and soybean cropping systems across SSA, and even fewer the biogeochemical factors that cause it ( Kihara et al, 2015 , 2016 ; Ronner et al, 2016 ; Njoroge et al, 2018 ; Shehu et al, 2018 ; Ichami et al, 2019 ).…”

Prediction of Maize Yields from In-Season GreenSeeker Normalized Difference Vegetation Index and Dry Biomass as Influenced by Different Nutrient Combinations

“…There was no significant interaction effect observed between site and nutrient combinations. The positive effect of combining primary, secondary, and trace nutrients on grain yields has been confirmed in Ghana by Kugbe et al (2019) and in Kenya by Muthaura et al (2017), Njoroge et al (2018), and Otieno (2019). Secondary and micro-nutrients are increasingly becoming important in Kenyan soils.…”