## 1 Introduction  
Phosphorus is one of the essential macronutrients that crops need for their growth and development. Adequate supply of P from the early growth stage of crops is vital for crop general health, improvement of crop quality, and optimum crop productivity. Phosphorus deficiency may limit crop yield, whereas build-up of excess P may cause P leaching and eutrophication of water bodies. In acid soils of the tropics, intense weathering of Ultisols and Oxisols which is influenced by high rainfall and temperature throughout the year results in low soil pH (ranges from 4 to 5), high leaching of bases, and replacement of bases in the with Fe and Al. Another consequence of intense weathering of these soils is that with time they become low in P availability with a high P fixing capacity because of their richness in Fe and Al ions which are known to have high affinity for P through a chemical reaction called P fixation. Thus, a large amount of P fertilizers are applied to saturate the capacity for P sorption with the ultimate aim of ensuring P availability for optimum crop uptake. However, this practice in agriculture is neither economically nor environmentally friendly. An evidence being that only 10-20% of P applied is available for crop uptake, whereas the remaining soil P (residual P) is adsorbed on soil constituents. Eventually, this could lead to a build-up of soil P capital in the year of application. Residual P is partitioned into different fractions and pools [1], namely, labile, moderately labile, moderately recalcitrant, available, and total P fractions. These P fractions' mobility, bioavailability, and chemical reactions may be remarkably different and can be transformed under certain conditions [2]. Thus, it could potentially infer distinct negative impacts on the environment as bioavailability for crops. Phosphatic fertilizers which originate from weathering of rocks are limited in reserves and might be depleted in 50-100 years [3; 4; 5; 6]. Responses to P scarcity may include increased cost, more efficient P use, P recovery, and P re-use. Moreover, prolonged use of chemical fertilizers in agriculture degrades soil fertility. Therefore, an effective management of P fertilizers will promote not only increase in crop yield but it will also reduce costs of production and mitigate environmental pollution besides conserving finite P deposit. Soil amendments being either organic or inorganic materials have been integrated in some agricultural practices. One of the soil amendments is natural zeolite, and Clinoptilolite zeolite (CZ) is the most common and abundant type of zeolites. Zeolites are natural aluminosilicates which have an infinite three-dimensional crystal structure, a polyedric shape, with a great open cavity [7; 8; 9]. These abundant and cheap minerals formed as a result of volcanic activities and have been extensively used in agriculture as soil conditioners, slow-release fertilizers, and soil decontaminants [10]. The use of zeolites and rock phosphate (RP) releases P through an exchange-induced dissolution system [11]. Uptake of cations in crops from CZ leads to vacant exchange sites which are capable of attracting Ca\({}^{2+}\) ions. This process lowers the activity of Ca\({}^{2+}\) ions from soil solution, thereby inducing dissolution of rock phosphates (RP) as well as producing ammonium ion as a by-product [12; 13; 14]. Because zeolites are not easily degraded over time, their persistence in soils improve nutrient retention and release for crop use [15; 16; 17]. Moreover, the catalytic ability of CZ could ameliorate soil pH, consequently reducing soil acidity and concentrations of exchangeable Al and Fe. This process does not only reduce P fixation in acid soils but it also ensures an efficient use of nutrients through timely release of nutrients for optimum crop production. It is possible that, in a long-term application of zeolites, soil properties could be rejuvenated to sustain crop productivity because zeolites can positively change the chemical dynamics of soils.