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In acid soils of the humid tropics, Phosphorus (P) deficiency due to its fixation by Al and Fe is common. It is therefore important to ensure adequate supply of P for optimum crop production. The use of zeolite on acid soils could fix Al and Fe and thus, rendering P readily available for crop use. The objective of the study was to determine the effects of including clinoptilolite zeolite in Zea mays cultivation on an acid soil on selected soil chemical properties, dry matter production, nutrient uptake and use efficiency of Zea mays. Triple Super Phosphate (TSP), urea and Muriate of Potash (MOP) were used in this study. Twenty five percent of the recommended N, P and K fertilizers for Zea mays were replaced with Clinoptilolite zeolite. Standard procedures were used to determine soil pH, exchangeable ammonium, available nitrate, available phosphorus, exchangeable aluminium, iron, cations and organic matter before and after planting. The plants were harvested at tasselling stage and measured for dry matter production, nutrients uptake and use efficiency. The effect of zeolite application with 75% of fertilization (T2) and 100% fertilization (T1) on soil chemical properties were statistically similar. Similar observation was made on dry matter production, nutrients concentration, nutrients uptake and nutrients use efficiency. The findings reported in this paper indicate that Clinoptilolite zeolite could be used to reduce the use of N, P and K fertilizers use of Zea mays on acid soils. At least three cropping cycles are recommended to confirm the findings of this study. It is also essential to estimate the economic benefits of including zeolite in Zea mays cultivation. These aspects are being investigated in on-going field trial.

Ammonia volatilization from urea and ammonium containing compound fertilizers cause higher cost of fertilization in agriculture. In this study, an incubation experiment was carried out to compare the effect of different ratios of compound fertilizer amended with clinoptilolite zeolite on NH3 volatilization, soil exchangeable NH4 and available NO3 contents on Bekenu Series (Tipik Tualemkuts) with surface-applied urea without additives. Treatments with zeolite significantly reduced NH3 loss when compared with urea without addictives. They also improved retention of exchangeable NH4 and NO3 and this was possible because zeolite favoured formation of ammonium and nitrate over ammonia. There is a potential for compound fertilizer with zeolite to improve nitrogen efficiency by lowering ammonia volatilization and increasing accumulation of exchangeable NH4 and NO3. Key words: Ammonia volatilization, compound fertilizers, clinoptilolite zeolite, soil exchangeable ammonium, available nitrate.

Problem statement: Exchangeable ammonium (NH4+) could be recovered by humic and fulvic acids from humic substances. The ability of these acids in fixing or retaining NH4+ has been demonstrated in many findings and reports. Both acids could affect the plant growth, nutrients uptake by enhancing photosynthesis rate and root growth among others. Thus, in this study, the effect of both acids (in liquid form) on soil exchangeable NH4+, dry matter production and available nitrate (NO3-) was investigated. Approach: Humic molecules were isolated using standard procedures, followed by liquid organic N fertilizers formulation. Organic based N fertilizers were applied to soil in pots at 10 Days After Planting (DAP) and 28 DAP. Treated soils and plant parts were sampled at 54 DAP or at tasselling stage. Soil samples were analyzed for pH, ammonium and nitrate content. The plant samples were weighed to assess dry matter production. Results: Under acid condition, organic based liquid N fertilizers (fulvic acid or both, humic and fulvic acids) increased accumulation of NH4+in soil. The presence of carboxylic groups in humic molecules increased NH4+ retention with increasing soil's stock labile carbon. However, low percentage of these acids reduced their full effect on dry matter production. The availability of nitrate was not statistically different for all treatments. Low soil pH could had reduced nitrification processes and simultaneously soil NO3- content. Conclusion: Liquid form of humic and/or fulvic acids could play an important role in enhancing urea efficiency. However, their contribution needs to be studied in detail in relation to humic molecules characteristics. This study had a potential in the development of liquid and foliar organic fertilizers.

Ammonia volatilization is a direct loss of available nitrogen in agriculture. The objective of this study was to determine the effect of amending NPK fertilizer with different rates of clinoptilolite zeolite on ammonia volatilization, soil exchangeable ammonium, and available nitrate. Seven treatments evaluated were: 250 g soil alone (T1), 3.28 g ammonium nitrate (AN) without additive (T2), 44.6 g 5:3:2 formulated fertilizer + 31.77 g zeolite (T3), 44.6 g 5:5:5 formulated fertilizer + 26.36 g zeolite (T4), 37.17 g 6:6:6 formulated fertilizer + 18.92 g zeolite (T5), 22.30 g 10:10:10 formulated fertilizer + 4.06 g zeolite (T6), and 14.87 g 15:15:15 commercial fertilizer (T7). The ammonia loss was measured using close-dynamic air flow system method. Soil pH, exchangeable ammonium and available nitrate at the end of this study were determined using standard procedures. The mixture of formulated fertilizer and zeolite significantly reduced ammonia volatilization. Zeolite in the formulated compound fertilizers did not significantly affect soil exchangeable ammonium and available nitrate. Amending N, P, and K compound fertilizer could minimize ammonia loss. Keywords: Ammonium nitrate, zeolite, ammonia volatilization, soil exchangeable ammonium, soil available nitrate

Application of crude humin with urea and Egyptian rock phosphate (ERP) may reduce ammonia loss from urea. This study was conducted to determine the effect of mixing crude humin with urea and ERP on ammonia volatilization and selected soil chemical properties. Crude humin from four different composts was mixed with urea and ERP and ammonia loss from these treatments were evaluated using the closed-dynamic air flow system. Standard procedures were used to determine ammonia loss, soil pH, total nitrogen, exchangeable ammonium, available nitrate, exchangeable phosphorus, cations, organic matter, total organic carbon and cation exchange capacity. Amending urea with crude humin had no effect on total amount of ammonia loss. However, addition of the crude humin significantly increased pH, organic matter, total organic carbon, cation exchange capacity (CEC) and exchangeable cations of Bekenu series (Tipik Tualemkuts). Crude humin from selected waste compost can be used to improve soil chemical properties.

Adoption of new management techniques, such as clinoptilolite zeolite (CZ) utilization has attracted muchattention in the fertilizer industry. Accordingly, the aims of this study is to evaluate: if CZ, acting as an inertmaterial, when applied to the soil, might improve the selected soil properties, height, dry matter, nutrientconcentration, nutrient uptake, nutrient use efficiency on maize cultivation; the potential for (N:P:K) compoundfertilizer when incorporated with CZ to serve same standard as the commercial fertilizer in fertilizer industry.The effect of T1, T3 and T6 on soil total N was found to be significant, when compared with T7. Treatments withCZ on soil total P, K and available P, K differed significantly relatively to T1 and T7. The treatments T5 and T6had the highest accumulation of exchangeable NH4+ and available NO3- relatively to T1 and T7. The significanteffect of the treatments having CZ on N concentration, in uptake and use efficiency, suggests that CZincorporated with fertilizer can reduce NH3 loss, triggering the formation of NH4+ and NO3- over ammonia andincrease maize uptake. Relatively to P concentration, uptake and use efficiency, it was found that in mosttreatments having CZ, lower values were obtained, relatively to the commercial fertilizer, although T3 clearlyimproved P uptake in roots. Most of the treatments with CZ remained statistically similar in K concentration,uptake and use efficiency compared to commercial fertilizer. It may be concluded that treatments with higheramounts clinoptilolite zeolite ensured good retention of soil exchangeable cations, available P, and NO3- withinthe soil. Treatments with CZ improved N uptake and use efficiency in the maize crop tested.