Integrated Soil Fertility Management in Improving Maize Production in Ethiopia

Review Article

Austin J Plant Bio. 2024; 10(1): 1047.

Integrated Soil Fertility Management in Improving Maize Production in Ethiopia

Deresa Shumi*

Oromia Agricultural Research Institute, Bore Agricultural Research Center, Ethiopia.

*Corresponding author: Deresa Shumi Oromia Agricultural Research Institute, Bore Agricultural Research Center, PO Box 21, Bore, Ethiopia. Email: deresashumi@gmail.com

Received: January 26, 2024 Accepted: March 08, 2024 Published: March 15, 2024

Abstract

The productivity of maize in potential agro-ecologies has been notified in decreasing trends, mainly because of declining soil fertility. To alleviate this production problem in the country, commercial fertilizers have been relied to boost the productivity of maize that commonly cultivated in continuous production system. The research outputs of various institutions in the country confirmed variable results because of differences in soil types, agro-ecology, varieties used and crop management systems. Maize planted using combinations of FYM, compost, biogas effluent, crops with lower rates of NP fertilizers at Bako and enriching FYM at Chiro with inorganic fertilizers gave comparable yield to the recommended NP rates. The uses of legumes as short fallows and green manuring indicated that mucuna at Bako and sesbania at Jimma, planted Legumes as precursor crop at Bako could partially or fully replace the N-fertilizer need of subsequently sown maize. At Hawassa also nine t ha-1 coffees by product combined with 60 kg N ha-1enhanced soil fertility and promised sustainable production of maize in respective location.

Keywords: Compost; FYM; ISFM; Maize

Introduction

Maize (Zea mays L.) is one of an important food crops in Ethiopia. It is also the most important cereal crop in terms of area coverage, production, and economic importance in Ethiopia [14]. According to ATA (2013/14) maize occupied 2 million hectares (ha) of land with estimated average yield of 3.2 tons (t) ha-1. This is far below the world average 5.1 t ha-1 [10]. One of the major constraints affecting maize production and productivity is declining soil fertility and inadequate crop management [9].

In Ethiopia, Maize is cultivated in all of the major agro ecology zones up to altitudes of 2400m.as.l. The maize growing areas in Ethiopia are broadly classified in to four ecological zones; high altitude moist (1800-2400 m.a.s.l.), mid altitudes moist (1000-1800 m.a.s.l.), low moist (below 1000 m.a.s.l.) and moisture stress (500-1800 m.a.s.l.) [8]. In this agro-ecology, pressure on land to put under cultivation has been increased in time series with raising population and following by gradual reductions of fallow periods. In addition, maize has been cultivated continuously on the same piece of land and most of these areas are characterized by cereal-livestock farming systems where free grazing animals remove more of crop residues than are returned in to soils for nutrient recycling, and aggravate soil erosion and high loss of nutrients [30]. It has also been observed that crop rotations are very rarely practiced and legumes are absent in the system [24]. However, commercial fertilizers have been relied to boost the productivity of maize in continuous cropping systems. Eventually, escalating costs of inorganic fertilizers may not encourage the purchasing potential of resource poor farmers. In this trend most farmers use to apply sub-optimal doses of fertilizers to their crops.

To restrain this emerging problem in the country, the use of mineral fertilizers has started since 1952 following the establishment of agricultural schools and experimental stations. Subsequent, extensive and nation-wide fertilizer studies have been made by different organizations [17]. According to the same source these earlier efforts have resulted in a blanket recommendation of 100 kg DAP ha-1 for most cultivated crops in all agro-ecologies of the country. The two types of fertilizers namely; urea and DAP (Diammonium phosphate) have been widely used than any other fertilizer in the country [6]. Moreover, most recent mineral fertilizer research attempts that have been done on maize at different research institutions confirmed variable results, mainly because of differences in soil types, agro-ecology, varieties used and crop management systems. Therefore, salient mineral fertilizer recommendations that primarily based on N and P rates have been offered for different maize producing regions of Ethiopia [29]. Although, continuous use of commercial fertilizers alone has caused adverse effect on soil nutrient balances and, reduced plant growth performance. Moreover, the use of chemical fertilizers alone might have also resulted in a possible depletion of essential micronutrients thereby resulting in an overall reduction in total crop productivity. This further justifies the need to use organic fertilizers. Research efforts made on different sources of organic fertilizers to show bright scenario for maize production in smallholder fields [34]. This authors reported that legume rotations, integrated use of mineral and organic fertilizers, green manure legumes resulted in enhanced soil fertility and promised smallholder farmers to produce maize at low cost. In addition they help to increase organic matter content of the soil which in turn improves the physic-chemical characteristics of the soil notably, increase water holding capacity of the soil. They also improve the nutrient retention property of the soil serve as reservoir of the micronutrients and reduce leaching losses of nutrients [31]. Besides, they increase the fertilizer use efficiency of crops [13].

Modern nutrient management strategy has shifted its focus towards the concept of sustainability and eco-friendliness. Integrated use of various soil fertility amendment inputs aims at alleviating the limiting nutrients problem and improves their availability through interactions with the mineral soil and reducing the P adsorption capacity of the soil. The integrated nutrient management paradigm acknowledges the need for both organic and inorganic mineral inputs to sustain soil health and crop production due to positive interactions and complementarities between them [20]. The objective of this paper is to review integrated soil fertility management options for sustainable maize production in Ethiopia.

Literature Review

Indigenous Knowledge of Maintaining Soil Fertility

Being in the tropics, most Ethiopian soils are very poor in their inherent soil fertility [18]. However, they were able to sustain crop production in the far past due to useful indigenous knowledge of soil fertility restoring practices mainly shifting cultivation, manuring, use of various food legumes mainly in the maize-based cropping system and the retention of crop residues after crop harvest in the farms [4]. However, some four decades back these traditional and natural ways of soil fertility restoration practices have been abandoned adversely affecting crop production. A brief description is given of these methods and their role on mainta in soil fertility is discussed.

Shifting Cultivation: In most parts of sub-Saharan Africa and indeed the eastern Africa region, the most common traditional farming systems were all variations of shifting cultivation [12]. In these traditional cultivation systems, recuperation of soil fertility was accomplished within a period of 15-20 years bush fallow which allowed crops to be grown without the use of fertilizers [21].

The shifting cultivation involved clearing part of the forest vegetation (approximately 0.5 ha), followed by burning when the mass of vegetation was dry and leaving the ash on the surface. Planting was done using digging sticks after the onset of the rains and weeding was done by slashing. The soils were therefore not disturbed between planting holes. Cultivation was done for 3-4 years and the fields would be abandoned. A bush would then develop from the stumps and large roots left after clearing the previous fallow and seeds from adjoin forest [11]. The regrowth of the secondary forest, initially composed of light-loving plant species, would then develop followed by slower-growing species and after 20 years the secondary forests were indistinguishable from the original forests [3]. The major mechanisms of nutrient transfer from the vegetation to the soil during the development of the secondary forest are mainly, stem flow, litter fall, timber fall and root decomposition. With adequate fallow periods of 15-20 years and a low population pressure density, shifting cultivation was capable of maintaining crop production and soil fertility [20]. With the increase in population pressure, the fallow periods are in most cases absent or too short to regenerate soil fertility adequately for improved crop productivity.

Application of Farmyard Manures: Applying Farm Yard Manure (FYM) locally called as ‘Dike’ is one of the most useful and significant indigenous methods practiced almost in all the villages of the country. Application of FYM is a practice which involves using of fully decomposed organic matter of livestock dung, straw, grasses, left over feed etc. The leaves used for animal bedding are also used for making organic manure. The preference towards leaves used for cattle bedding depends upon the availability of resources in nearby forests. The quantity of FYM used for field application depends upon the number of livestock reared, proximity to the forest, extent of land as well as the manpower available. With the application of FYM, earthworms also get introduced in the cropland and increase the fertility of the soil.FYM has been used in many parts of sub-Saharan Africa as a key resource for sustaining soil fertility. Manures are an important source of major and minor nutrients and have also been used to improve soil physical and chemical properties [22] FYM therefore play a major role in improving crop productivity for the resource poor farmers of the sub-Saharan Africa.

Mixed Cropping and Crop Rotation

In the past, farmers within the central Ethiopian highlands used to grow a wide range of food legumes, mainly intercropped with maize. The legumes included cowpeas (Vigna unguiculata L.), pigeon peas (Cajanus cajan L.) and dry beans (Phaseolus vulgaris L.). Legumes root symbioses provide N2 through biological nitrogen fixation. The legumes can therefore use fixed N rather than soil mineral N [2].

Legumes cannot always supply enough N to meet all the internal plant needs by symbiotic nitrogen fixation. This is true for legumes because, nodule activity decreases during the grain filling period when there is an increasing completion of reproductive structures with the nodules for a diminishing photosynthetic supply. Nevertheless, some food legumes are more efficient in N2 fixation than others under a given set of environmental conditions. For example, cowpeas are estimated to fix between 73-80 kg N ha-1, pigeon peas between 65-85 kg N, while dry beans inoculated or un inoculated have sometimes failed to fix N [19].

Modern Concept of Maintaining Soil Fertility

Integrated Nutrients Management:

Integrated Use of Cropping Systems with Inorganic Fertilizers and Farmyard Manure: Low soil fertility is one of the major factors limiting crop production and productivity in small holder maize based cropping systems in Ethiopia. Inorganic inputs fertilizers in continuous cropping systems have limited ability for long-term maintenance of soil fertility [35]. Legume-cereal sequence is one of the cropping pattern practices on smallholder farmers' in Ethiopia. Crop rotation sequences incorporating legumes can be used to effectively restore, maintain, enhance soil fertility and built up the N status of the soil. Besides, reduced dependence on chemical fertilizers crop rotations that favour nitrogen fixation will benefit both agriculture and environment and should be integrated in cropping systems [35].

The study carried out at Western Oromia, on identifying the best precursor crops and optimum integrated of farmyard manure and inorganic fertilizer in maize based rotation sequence show that Haricot bean, Niger seed followed by application of either 12 t ha-1FYM or 89-35NP2O5 kg ha-1 is a better option for sustainable maize production than continuous mono cropping [1]. The study carried out by the same authors on similar location on best compatible soybean varieties in intercropping systems and the most economically optimum integrated fertilizer from soybean (Didessa variety) without affecting yield of the maize.rate show that were significant differences in leaf area index, plant height and grain yield of maize due to integrated fertilizer application. Integrated use of 55/23 N/P2O5 kg ha-1 with 8 t ha-1 FYM also revealed better economic advantage with some additional yield

Integrated use of inorganic and organic fertilizers: Integrated use of organic and inorganic fertilizers is much better than single use of either chemical fertilizer or organic ones in maize cropping systems. It increases fertilizer use efficiency, reduces risks of acidification, and provides a more balanced supply of nutrients [28]. Organic manures and residue also improve physical and chemical properties of soil and fertilizer use efficiency when applied in combination with mineral fertilizers [5]. There are a number of researches done by different scholars to address the problems of soil fertility, on locally available sources of organic fertilizers for continuous basis for replenishing the degraded physicochemical properties of soils to make sustainable maize production in Ethiopia. Accordingly, a study carried out on integrated uses of NP and FYM at five locations in western Oromia indicated that integrated application are better than application either NP or FYM alone [33] (Table 1). Other studies at the same location revealed that FYM has to be applied every three years at the rate of 16 t ha-1 supplemented by NP fertilizer annually at the rate of 20-46 N-P2O5 kg ha-1 (Table 2) for sustainable maize production around Bako and similar areas [27].