Organic Fertilizers Use and Application for Cereal Crop Production in Ethiopia

Different relevant studies have been held across the county parts or regions to assess the effect different organic fertilizers like compost, farm yard manure, green manure, crop residue and biogas slurry application and use in experiment field and smallholder farming without upsetting their usual living. Results supposed to the benefit of farmers and come up with a policy briefing that policy makers give a better support for its implementation. The experiments conducted in different regions by different researchers like Maichew District of Tigray Region by Hailu Araya, Gozamen Woreda Eastern Gojam Amhara Region by Tadesse Dejene , Haraghe zone Oromia region Easten Ethiopia by Zelalem Bekeko and Sirinka Earstern Amara rgegion by Abebe Getu and Yalemtshay debebe in Sebeta Oromia Region indicated that the application compost Farm yard manure ,green manure and Biogas slurry enhances different crop production and productivity by improving of soil physical and chemical property and also bring additional benefit in terms of minimizing inorganic fertilizers cost. Therefore this visualized or tell us for the future as country level promoting of organic fertilizers in well-organized form is very important to enhance cereal crop productivity and there quality by improving soil and soil fertility issues.

gives 1,478 (N), 540 (P) and 940 (K) kg.ha-1 (Table 1). These applications are much higher than the usual macronutrient applications through organic and inorganic fertilizers. Table1.Compost application rates (t.ha-1.yr-1) and their corresponding nutrients (kg.ha-1.yr-1) Application rate t/ha Nutrient application kg. Studies show composts contain about 12-20 percent organic carbon (Asmelash, 2001), which are sources of energy for bacteria, fungi, earthworms and other organisms in the soil. They break-down dead plant and animal remains by releasing carbon dioxide, water and mineral salts, including nitrates, phosphates, etc., which are the nutrients for growing plants (Asmelash, 2001). The nitrogen content of compost is reported as high as15.3g.kg -1 (Wahba, 2007).Carbon: Nitrogen (C/N) ratio <21 is compost maturity indicator (Getinet et al., 2008). From a study by Manna et al., (2001) in the semi-arid tropics of India C: N ratios of 8-22. Compost with a higher C: N ratio is not recommended for application because C: N ratio >15 is an indication of limited N availability due to immobilization.
In matured compost the lowest C: N ratio, below 6-7 (Gutser et al., 2005) is an indication of materials to be humified and stable. They are suitable for field application, Improving N and C: N ratio of compost is related to the proportion of the green plants and dry materials used for the compost-making. The optimum C: N proportion of different composting materials is 30:1 (Getinet et al., 2008). Because composting has high carbon materials additional nitrogen (mineral fertilizer) may be required to reduce the C: N ratio to the optimal range. It facilitates the establishment of micro-organisms for the quick decomposition of biomass into compost. Generally dry materials (woody materials or dead leaves) have higher C: N ratios while green materials usually have lower C: N ratios. This is because the dry, coarse materials such as straw, wood chips, etc. are high in C and low in N while the green materials such as grass clippings, fresh plant material, kitchen scarps and manure, are high in nitrogen and low in carbon. Animal wastes are also more N rich than plants (Cyber-north, 2004).

Compost Production capacity
The compost production capacity of farmers varies very much. It varies from farmer to farmer mainly dependent on the animal holding (Tulema et al., 2007). This is because animal feed waste and animal manure are available best to the farmers who own cattle (Kikafunda et al., 2001). According to Manyong et al., (2001) more livestock holding encourages families to use organic manure and owning domestic animals are common in Africa. The availability of biomass in Ethiopia is estimated to 22.7x10 6 t.yr -1 of dry manure, 12.7x10 6 t.yr -1 crop-residue and various other organic by-products (Tulema et al., 2007). While the study by Devi et al., (2007) reported that recyclable resources in Ethiopia are abundant. They estimated the total amount available as 1.6x10 11 t.yr -1 (compost/vermicomposting), 8.5x10 9 t.yr -1 (poultry manure) and 1.8x10 10 t.yr -1 (FYM).
While the required amounts for the total agricultural land per year is 3.25x10 10 t.yr -1 (compost/vermicomposting), 3.2x10 9 t.yr -1 (poultry manure) and 9.7x10 7 t.yr -1 (FYM) (Devi et al., 2007). This is mainly because Ethiopia is the highest in livestock population in Africa (Zinash, 2001). Biomass availability in moisture stress areas is dependent in the biomass management. For example, farmers keep manure accumulated in cattle pen until it is cleaned or used for composting (Miner et al., 2001). Manure management increases not only the quantity but also the quality of the manure (Lekasi et al., 2001). But the production capacity varies based on the animal holding. However, so far the production capacity of compost is not studied at family level.

Compost application by smallholder farmers
The rate of application of organic manure differs according to the climatic conditions of the area. In the western part of Ethiopia the recommended application rate is 8-12 t/ha but in other areas applying 3.5-6.0 t/ha can give good yield (Fentaw, 2010).The average amount of compost application ranged from 5-15 t/ha, depending on availability of materials (Menale et al, 2009).According to Hailu Araya (2010) Over 88% of the farmers in Tigray region Maychew use compost. About 39 percent of them produce between 1 and 2 t compost annually (Figure 1). The average cultivated landholding of the area is 0.8 hectare per family, which is fragmented into two or more pieces. The average amount of compost sieved and weighed from one 1.0mx1.5mx1.5m pit is 800kg i.e., 16-18 Qumta (a traditional quantity measurement sack equivalent with 50 kg). Usually it is used in one plot of land, which is called Tsimdi/Kert (equivalent with 0.25 hectare).
However, the amount of compost applied per unit area varies based on the type of the soil and crop. But generally more compost is applied in sandy soil and for higher plants, while less amount of compost is applied in clay soil and for smaller plants. For example, when a field is sown with teff, which is a very small type of crop, the application of compost is 2.8 t.ha -1 in clay soil and 4.8 t.ha -1 in sandy soil. On the other hand when a field is sown with barley, wheat or finger millet higher amounts of compost is applied than they apply for teff (Table2). According to the farmers this is important application amount because they are getting better yield without lodging problem in the different crops.
Over 39 percent farmers used mix compost and animal manure with mineral fertilizer. 24 percent of the farmers prepare and use only compost and 13.5 percent use only animal manure in their fields. There are only 13.5 percent farmers who use mineral fertilizer alone in their fields. About 10 percent they do not use any type of input in their farms. It is because they have fertile fields, which does not need any input to be applied (Hailu Araya, 2010).

Effect of Compost on Yield of Cereals
Compost enhances soil fertility, soil structure and water storage capacity for two or more years, unlike inorganic fertilizer (Fentaw, 2010). Jagadeeswari and Kumaraswamy (2000) noted that use of composts with mineral fertilizer increased yield and production of wheat, green beans, gram and rice. Grain and straw yields of rice were significantly higher in amendments that received compost application with NPK than in no compost with NPK amendments, thereby highlighting the beneficial effects of compost to increase the crop yield.
The study conducted ada'a district Eastern Shewa Oromia region by Genizeb Ayaye (2015) indicated that ;The grain yield value of bread wheat 666.67 gm -2 or 66.67 Qt/ha was recorded in the application of dry matter compost along with inorganic fertilizers . However, the lowest grain yield (260 gm -2 or 26 Qt/ha) was obtained under control field or plot .Similar Research which conducted by Hailu Araya in Tigray region grain yields of teff and barley from plots applied with mineral fertilizer and 6.4 t.ha -1 .yr -1 compost show they are significantly higher than the 3.2 t.ha-1.yr -1 compost application and the control plots.
But there is no significant difference between the 6.4 t.ha -1 compost and the mineral fertilizer applied plots. The grain yield between 3.2 t.ha-1.yr -1 compost and control plot indicated that compost application is better than the control plots. Other findings of Getachew et al. (2012) also revealed that efficient management and utilization of organic nutrient sources and the required inorganic fertilizers in correct balance may contribute to longer-term sustainability of agricultural productivity and an integrated farming system in the highlands Ethiopia, where soil erosion is serious and the resultant soil fertility depletion is alarming. This shows that the potential for continuous crop production on these soils is very limited in the absence of soil amendments or use of organic fertilizers.

Crop residue
Crop residues have a number of functions. When left in the field after grain harvesting, crop residues play a significant role in nutrient cycling, soil and water conservation, maintenance of favorable soil properties, and enhance subsequent crop yields. Other benefits of retaining crop residues on the soil surface include an increase of organic matter and nutrient levels, moderation of soil temperature and increased soil biological activity, all of which are important for sustaining crop production.
Crop residues are also used for other purposes, such as to provide vital livestock feeds during long dry seasons, fuel and construction material (Latham, 1997). Use of crop residues as a soil amendment is often limited due to its obstacle to mechanical and hand tillage, negative effects on crop productivity arising from incidence and carryover of pests (Ferdu et al., 2002), diseases (Tewabech et al., 2002), allelopathy and short term nutrient deficiency (Ocio et al., 1991). For these reasons, much of crop residues are either fed to cattle or burnt.
When all crop residues are used as animal feed or removed for other purposes, the above mentioned soil related benefits are lost. As a result, sustaining soil productivity becomes more difficult. Crop residues contains large quantities of plant nutrients and, if properly managed and returned to the soil from which it was grown, could serve as an effective means of maintaining the organic matter and nutrient levels in soil. recycling of crop residues is especially important in developing like Ethiopia countries because: (i) the amount of the nutrients in crop residues are seven to eight times higher than the quantity of nutrients applied as fertilizers, (ii) crop residues is a source of trace elements which are absent in the commercial NPK fertilizers and (iii) organic and inorganic materials have a complementary role and their simultaneous use will ensure better crop yields.
Proper usage of crop residues could therefore result in less importation of chemical fertilizers with great savings in scarce foreign exchange. In most countries of Africa the nutrient balances of cropping systems are negative, with off take being greater than input, indicating that farmers are mining the soils. Larson et al. (1972) estimated that crop residues contain on average 40, 10, and 80% of the N, P, and K currently applied as fertilizer. For example a ton of maize residue contains 4-8 kg N, 1.5-1.8 kg P, 13-16 kg K, 3.8-6.6 kg Ca, and 1.5-3.4 kg Mg. Residues of cereal crops comprise 60 to 75 % of the total biomass production and have lower nutrient concentrations than the grain (Van Duivenbooden, 1992). Therefore, returning of them to the soil systems particularly, where no or low inputs are used, is essential in slowing down nutrient losses. However, crop residues by themselves are not enough to offset nutrient mining in sub-Saharan Africa. Crop residue management influences the availability of nutrients especially N.
According to the study conducted by Tadesse Dejene (2011) In Gozamen Woreda Eastern Gojam Amhara Region, crop residues are commonly used for maintaining soil fertility and crop production in two ways. The first one is through shifting of animal feeding beds. In this case, farmers feed their cattle in different parts of their farm plots at different times. The common fodders of the cattle are grasses and straws or crop residues. While animals are feeding, there are remnants left on the soil and are through time biologically decomposed during farmland preparations. Shifting animal feeding places is duly important for addressing the whole parts of the farm plots, but because of its laboriousness, this method is mostly, applied in the nearby farmlands of the homesteads locally known as guaro, where livestock are usually kept.
The second method is shifting of threshing floors locally called Audima. In these both systems crop residues are mixed with soils during ploughing. However, farmers explained that it takes time to use crop residues as fertilizer since it requires a long period of time for decomposition to take place, but can be practiced in every farm plot. The farmers on the other side advise that crop residues negatively affect farmlands' productivity in different ways. For example residues like maize stalks and wheat residues can transmit crop diseases from place to place and enable these diseases to sustain their life until the next cropping season. If crop residues stay for a long period of time not decomposed, it will be comfortable for rodents breeding. Besides, they argue that since the most important sources of animal feeding are crop residues, using crop residues as fertilizer affects livestock production.

Farm Yard Manure
Animal manures are valuable sources of nutrients and the yield-increasing effect of manure is well established. Apart from the nutrients in manure, its effects on the improvement of soil organic matter, soil structure and the biological life of the soil are well recognized particularly at high rates of application in on-station trials. There is also some evidence that it may contain other growth-promoting substances like natural hormones and B vitamins (Leonard, 1986). Crop quality has also been improved by manure application (Pimpini et al., 1992).
When crop improvements with manure were greater than those attained with commercial fertilizer, response was usually attributed to manure supplied nutrients or to improved soil not provided by commercial fertilizer. It is also well known that the use of farmyard manure can reduce nutrient deficiency in soils. Koppen and Eich (1993) noted that K and P deficiencies were reduced when farmyard manure was applied, and with rising pH values, the Mn content of the soil declined. The potential of manure, especially poultry litter, to neutralize soil acidity and raise soil pH is less well known.
Application of animal manures to agricultural fields is a widely used in method of increasing soil organic matter, fertility and crop production (Wakene et al., 2005). Most solid livestock manures can be applied directly to crop fields or piled for composting. In organic farming, Nitrogen (N) is supplied through organic amendments in the form of manure. Applying organic N fertilizer without prior knowledge of N mineralization and crop needs can result in nitrate nitrogen (NO3 N) leaching below the root zone and potential groundwater contamination (Debelle et al., 2001). Soil fertility depletion on smallholder farms is one of the fundamental biophysical root causes responsible for declining food production in eastern part of Ethiopia (Ararsa., 2012).
Highlands of Hararghe, eastern Ethiopia, where maize is grown among the major cereals in the high rainfall areas such as (Chiro, Doba, Tullo, Mesela, Gemechis, Kuni, Boke Habro and Daro Labu) soil fertility depletion is the number one problem stagnating crop productivity including maize Misganw (2014). Intercropping is widely used in this area by combining maize or sorghum with perennial crops like Chat (Chata edulis) which further exposes the soil to rampant nutrient degradation leading to poor crop yield ( Ararsa, 2012). Due to this Crop residues and FYM are used for maize production .the low rates of NP fertilizers used for maize production under farmers' conditions have aggravated the situation of soil fertility degradation and declining maize production. Consequently, training the farming community on the proper handling and use of FYM together with low rates of inorganic fertilizers taken as alternative solution for fertility management in Hararghe Misganw (2014) .
Supplying of nutrients from chemical fertilizers has got certain limitations and inherent problems. Further, these chemical fertilizers can supply only a few plant nutrients like nitrogen, phosphorus and potash and also they are becoming very expensive for resource poor farmers. Silvia et al. (2006) reported that non-inclusion of organic manures such as FYM, compost, green manures, etc. in the manurial schedule have resulted in the depletion of fertility status of the arable soils and their consequent degradation. Debelle et al. (2001) also reported organic manures, especially FYM, have a significant role for maintaining and improving the chemical, physical and biological properties of soils and in sustaining maize yield in western part of Ethiopia. They also reported that 10 ton/ha of FYM are statistically at equivalence with current agronomic recommendation of inorganic fertilizers N and P for maize.
Another study by Zelalem Bekeko (2013) at Haraghe Zone Oromia Region Easten Ethiopia indicated that that 10 tons/ha of FYM and 100 kg/ha N + 100 kg/ha P showed no significant difference on maize grain yield but significantly differ from control Treatment (Table3). Wakene et al. (2005) also indicated that the urgency of using organic manure has been gaining ground in the wake of increasing cost of fertilizer with every passing year and certain other inherent limitations with the use of chemical fertilizers. FYM is the oldest organic manure used by man ever since he involved in farming. It has stood the test of time and is still very popular among the poor and marginal farmers.
It consists of litter, waste products of crops mixed with animal dung and urine.it contains all the nutrient elements present in the plant itself and returns these nutrients to the soil when it is applied to the field for the benefit of succeeding crop.  Vol.9, No.10, 2019 20 plants used for animal fodders is important farmland management to be practiced. It also includes the byproducts of local food production processes like atela and others which are daily swept out of a house in dirt forms. This is applied by (93.85%) of sample households (Table 4).According to Taddess (2011) most of the respondents or the farmers, used Farm yard manure with chemical fertilizers though they are not applied simultaneously. Unlike chemical fertilizers, manures are added to the soil long days ago before seeding either in the rainy or dry season. Nevertheless, it is mostly limited to farm plots which are nearer to homesteads, locally known as guaro, mainly due to long distance of the farm plots and this negatively affects soil fertility enhancement on farther farm plots.

Green manure
Acknowledge the positive contributions of green manures or cover crops and allocated to grow is relatively small In Ethiopian only few legumes are integrated to the system. In the perennial-based farming systems the only most dominant legume in the cropping is common beans, intercropped with maize or grown sole as a second crop. However, cultivation of beans may not contribute much to soil fertility improvement mainly. because the crop is harvested by uprooting the whole plant as it needs to be stored by hanging bundles on a trellis and kept indoors to avoid sprouting (Eyasu, 2002); no residue is returned to the soil as pods and tops are fed to livestock with the stalk is used as feed or cooking fuel and beans has the least N-fixing potential particularly in low pH soil with low P availability.
Legume green manure crops highly practicable especially in southern nations and nationality and peoples of Ethiopia for a short term fallow. The major biophysical criterion used for selection of cover crop species is a position to produce higher biomass under degraded corners of the farm (Tilahun Amede, 2003). Farmers were not interested to grow the Legume cover crops in the fertile corners, as they were allocated for food crops. The land they wanted to get improved are the border strips, the abandoned corners, steeply slopes and the barren land, where the land failed to produce any reasonable crop yield. But most of the Legume cover crops, with strong history in improving soil fertility, demand relatively fertile soils to establish, produce large amount of biomass and to fix atmospheric nitrogen.That is the reason why farmers selected crotalaria for improving degraded farmlands over mucuna, canavalia, tephrosia and vetch on individual farmer's field, Crotalaria was the best performing species regardless of soil fertility. Double cropping cereals with leguminous species have potential implications for the nitrogen requirement of and usage by the cereal component and, less frequently, on phosphorus use efficiency (Sinha et al 1983). The advantages of green manuring for increased crop productivity has also been reported elsewhere (Yeshanew and Asgelil, 1999). However, no work has been done so far in the region on the use and contribution of green manure to soil fertility improvement. The study conducted by Abebe Getu (2015) on the effect of green manure plants on sorghum Yield and soil fertility in eastern Amhara Region of Ethiopia revealed that there was statistically significant (P < 0.05) difference in the grain yield of sorghum due to the effect of intercropping with the green manures. However, there was no significant (p > 0.05) effect of intercropping green manures on the biomass weight of sorghum (Table 5). combined analysis over the two experimental years as shown in Table5 indicated that that the mean effect of intercropping green manures on the grain yield and biomass weight of sorghum were statistically significant (p < 0.05). Treatments within a column followed by the same letter are not significantly (p > 0.05) different; ns-non significant (p > 0.05).

Biogas Slurry
In response to the need for addressing the adverse impacts of the increasing trend in biomass energy consumption in Ethiopia, the last three recent decades have witnessed heightened interest in mobilizing national and international efforts towards the development of more efficient cooking stove technologies and alternative sources of household energy. Biogas as an alternative to the use of biomass for energy was introduced in Ethiopia since late 1970s even though on a fragmented manner and with limited success in penetration of the technology (Kidane et al., 2007). According to a feasibility study on domestic biogas in Ethiopia (Getachew et.al., 2006), for example, from approximately 1000 biogas plants constructed since the 1970s across the country only 40 percent were functioning at the time of the field visit.
In the same study (Getachew et al., 2006), the report indicated that at least over one million households in Tigray, Amhara, Oromiya and Southern Nations, Nationalities and Peoples regional states qualify for the installation of a domestic biogas plant. The domestic biogas technology attracted interest mainly due to consideration of the animal dung, the raw material that is plenty in many rural households in the country. After the establishment of the National Biogas Program Ethiopia in 2009, close to 859 biogas plants have been constructed and are in regular use. Out of the 859 functional biogas plants, 206 are found in Tigray Region, 143 are in Amhara Region, 330 in Oromiya Region and 180 are found in SNNP regional states (Claudia and Yitayal, 2011).
Application of bio-slurry in liquid and composted form alone at the rate of 20 t/ha or with full dose of chemical fertilizer at the rate of 10 t/ha increase the yield of maize, soybean, wheat, sun-flower, cotton, ground nut, cabbage and potato in different percentages over the controls (IFPRI, (2010)). The study by Dhobighat and Painyapani, (2006) indicated that the use of bio-slurry increased the yield of rice and maize by 34 percent and the yield of wheat by 25 percent. The use of bio-slurry in different forms improved not only the quantity but also the quality of yield of the crops, vegetables and fruits as well as the disease resistance capacity of the plants (Krishna, 2001).
The study conducted by Yalemtshay Debebe (2013) Comparative study on the effect of applying biogas slurry and inorganic fertilizer on soil properties, growth and yield of white cabbage (Brassica oleracea var. capitata f. alba) at Sebeta Hawas Woreda, South West Shewa zone Oromia Region indicated that combination of slurry compost and full dose of fertilizer (produced 38.4 percent higher yield than full dose of inorganic (Table 6). Likewise, the half dose of fertilizer with half ofthe slurry compost was 38.7 percent inferior to full dose of inorganic fertilizer with 80q/ha of slurry compost. This result is in line with the result of Singh et al. (1995) who reported that the combination of fertilizer and bio slurry significantly increased the yield of rice, corn, soybeans and okra.

Summary
The government of Ethiopia has launched an agricultural package during the previous decade focused on a package of mineral fertilizer and high yielding varieties to increase crop production. However, farmers have been unable to using mineral fertilizer because of the high price, weak delivery, and a sharp drop of crop prices after harvests and unreliable rainfall. Instead farmers are highly inclined into locally available soil fertility management and yield increment practices including composting, green manure, and farm yard manure, crop residue and biogas slurry because they require high labor and low capital, which are risk avoidance strategies of Ethiopian farmers. Different relevant studies have been held across the county parts or regions to assess the effect different organic fertilizers like compost, farm yard manure, green manure, crop residue and biogas slurry application and use in experiment field and smallholder farming without upsetting their usual living. Results supposed to the benefit of farmers and come up with a policy briefing that policy makers give a better support for its implementation. The experiments conducted in different regions by different researchers like Maichew District of Tigray Region by Hailu Araya, Gozamen Woreda Eastern Gojam Amhara Region by Tadesse Dejene , haraghe zone Oromia region Easten Ethiopia by Zelalem Bekeko and Sirinka Earstern Amara rgegion by Abebe Getu and Yalemtshay debebe in Sebeta Oromia Region indicated that the application compost Farm yard manure ,green manure and Biogas slurry enhances different crop production and productivity by improving of soil physical and chemical property and also bring additional benefit in terms of minimizing inorganic fertilizers cost. Therefore this revised seminar visualized or tell us for the future as country level promoting of organic fertilizers in well-organized form is very important to enhance cereal crop productivity and there quality by improving soil and soil fertility issues.