Evaluation of Biomass Yield and Nutritional Composition of Soybean (Glycine Max (L.)Merrill) Varieties Grown in Low Land Areas of Eastern Amhara, Ethiopia

The experiment was conducted in three locations Jari, Chefa and Sirinka of Eastern Amhara to select the best performing varieties, in terms of biomass yield, chemical composition, haulm yield, seed yield and other agronomic characteristics of Glycine max (L.) Merrill grown under the rain- fed condition of lowland areas of Eastern Amhara in a randomized complete block design with tree replications. Twelve released soybean varieties were Afgat ,Belesa-95, Boshe , Cheri , Dhidhessa, Gishama , Gizo, Korme, Pawe-03, katta, Wegayen and Wollo were used as a treatments. The seeds were planted in 40 cm between rows and 10 cm between plants on a plot size of 3.2m*4m. Spacing between blocks and plots were 1 and 0.5m, respectively. The seed rate was 60 kg/ha and a fertilizer rate 100 kg/ha NPS was applied during seed planting. The combined analysis of variance over two years at location Jari for dry matter yield of varieties Afgat, Gizo, Pawe-03, Wogayen and Wollo were significantly higher as compared to other soybean varieties. The combined analysis across locations at Jari and Sirinka (2019-second year) showed that varieties Afgat, Gishama, Gizo, Pawe-03, Wogayen and Wollo had higher dry matter yield and varieties Gishama (3.97 t/ha), Gizo (3.60 t/ha), Pawe-03 (4.04 t/ha) and Wogayen (3.36 t/ha) had higher haulm yield as compared with other varieties. The combined analysis across locations at Jari and Sirinka (2019) showed that varieties Pawe-03(2951 kg/ha), Gizo (2862 kg/ha), Afgat (2859 kg/ha), Gishama (2654 kg/ha),Wollo (2461 kg/ha) and Wogayen (2404 kg/ha) had higher seed yield as compared with other varieties. The variety Wollo gave higher crud protein content in two locations (Jari and Sirinka) .Therefore, varieties Afgat, Pawe-03 and Wollo were recommends for the given areas of Jari , Chefa, Sirinka and could be produced in similar environments for the best of produced optimal amount of dry matter, haulm and seed yield and good protein supplement for production of ruminants.Thus, further researches will be needed to investigate on the utilization of livestock.


Introduction
The low productivity of Ethiopian livestock is a result of several limiting factors among which feed is the major one.The country as a whole the existing feed does not meet the amount required by livestock. Natural pastures are the most important livestock feed resource. In most parts of the country natural grasslands are confined to degraded shallow upland/highland, fallow crop lands and soils that cannot be successfully cropped due to physical constraints such as flooding and water logging. They are low yielding and their production is insufficient and grazing conditions are only favorable for four to five months per year. For several decades, grazing areas have been shrinking and likely to continue to do so because of rapid expansion of cultivated land for crop production to provide food for the ever-increasing human population. As a result, there is always likely to be limited feed resources for the existing livestock population. Therefore, selection of high-yielding and better-quality forage varieties, and development of improved forage production systems are critically important (Alemayehu Mengistu and Getnet Assefa, 2012;Alemayehu Mengistu et al., 2016).
In the past four decades, extensive research and development has been carried out in Ethiopia to test and evaluate the adaptability and performance of different forage species under different agro-ecological zones. An array of potential grass, legume and browse tree forage species have been selected for development programs. The selected species showed better yield and quality than those in the naturally occurring swards. The introduction and development of selected forage species into the farming system was expected to help solve the severe forage deficit that the country is presently facing (Alemayehu Mengistu et al., 2016) .In the dry season, when available feed in the form of grazing ,hay and crop residues is not enough to support animal productivity , supplementation with forage legumes increases animal productivity (Murphy and Colucci, 1999). One among potential forage legume resources is the introduction and adoption of the soybean forage.
Soybean (Glycine max (L.) Merrill) is a major legume crop grown for its protein and oil rich seeds but it also makes valuable forage for grazing, silage and hay. It is a fast growing herbaceous annual native to Asia that is currently grown worldwide. It is an erect leguminous plant, which grows up to a height of 1.3 m. Like other forage legumes, soybean forage has many valuable traits as fodder. Soybean leaves and steams can be grazed. Ensiled or dried to make hay.
The foliage is very palatable to cattle and has a high nutritive value and good digestibility (Koivisto, 2006).
Ideally soybean forage is suited for Winnter cropping in Ethiopia; it is tolerant of drought and thrives when other forage legumes like alfalfa are not available. Forage soybean can be sown alone or in combination with other forage species such as sorghum (Fujita et al., 1990). It should be sown on a well prepared seed bed once average temperatures are higher than 10 o c. It grows quickly and can provide 5 to 10 t DM/ha within 3-4 months (Doo-Hong Min, 2012;Koivisto et al., 2003). It can be first grazed when it reaches 60 cm in height (Lugin buhl, 2006). The large increase in forage yield and small effect on forage quality associated with growing cultivars of later than normal maturity suggests that cultivars of later maturity, when compared to locally adapted cultivars for seed production, are often the best choice for soybean forage production (Hintz et al., 1992).
The nutritive value of soybean plant can be comparable to early bloom alfalfa (that shows high protein content and very digestible to mature ruminant animals). Lactating dairy cows and growing heifers can have similar performance when given either soybean hay or alfalfa forage.Palatability is not usually concern when feeding soybean forage (unless the forage is moldy or dusty). In three to four months after seeding it produces cut hay equal in quality to alfalfa cut hay (Hintz et al., 1992).
Soybean forage is relatively rich in protein, which varies between 11% and up to more than 22% of the DM. Fibre content is also quite variable, with ADF content ranging from 20% to more than 45% of the DM. It is relatively poor in lignin (about 6% DM). The main factor influencing soybean forage quality is the maturity at harvest. Protein concentration decreases during flowering and increases during pod formation, while fibre concentration changes inversely. The stem and leaf proportion of the plant decreases as the pod and seed components increase. The lipid content of the mature forage can reach 10% of the DM due to the presence of oil in the seeds (Hintz et al., 1992).
Haulms is plant material above the ground level, harvested, dried and used forfeeding livestock.
Grain legume haulms are also playing a significant role in supplying fodders for ruminant feeding in small scale mixed farming system. The highlands Ethiopia demonstrated increasing trends in the use of grain legumes haulms as livestock feed by smallholder farmers (Alkhlib et al., 2014). Soybean haulms (residue) have already became important components of ruminant diet in small scale mixed crop-livestock farming areas. Soybean haulms had also figured out value of 89.18, 5.10, 2.85, 96.90, 80.80, 63.20 and 13.00% for DM, CP, EE, OM, NDF, ADF and ADL contents, respectively (Maheri-Sis et al., 2011).The dry matter yiled of soybean haulm was 5.31 t/ha harvested with application of NPK followed by urea fertilizer, 4.31 t/ha with organic fertilizer (compost) and 4.29 t/ha with out any fertilizer (Yagoub et al., 2012) and 3.23 t/ha with fertilizer in (Sisay Belete,2017).This study carried out, therefore, to select the best performing varieties, in terms of biomass yield, chemical composition, haulm yield, seed yield and other agronomic characteristics of Glycine max (L.)Merrill grown under the rain-fed condition of low land areas of Eastern Amhara.

Description of the study area
The study was conducted in three locations Jari, Chefa and Sirinka of Eastern Amhara. Jari is situated at 11 0 21 ' 00 '' N latitude and 39 0 38 ' 00 '' E longitude located at about 435 km North of Addis Ababa Capital City of Ethiopia. It lies within an altitude of 1680 meter above sea level.
The area receives an average annual rain fall of 1204.6mm and a mean range temperature of 11.2-25.6 0 c. There is black soil type and clay soil texture. Chefa is located at about 355 km North of Addis Ababa Capital City of Ethiopia. It lies within an altitude of 1450 meter above sea level. The area receives an average annual rain fall of 850 mm and a mean range temperature of 21-36 0 c .There is black soil type and clay soil texture. Sirinka is situated at 11 0 45 ' 00 '' N latitude and 39 0 36 ' 36 '' E longitude located at about 508 km North of Addis Ababa Capital City of Ethiopia. It lies within an altitude of 1850 meter above sea level. The area receives an average annual rain fall of 950mm and a mean range temperature of 16-21 0 c. There is Eutric soil type and clay soil texture (Adem Mohammed et al.,2016).

Experimental procedures and design
The experimental fields were divided in to three blocks and the twelve treatments randomly assigned to the plots in each blocks using a randomized complete block design (RCBD). Twelve released soybean varieties were used as a treatment. Planting was done second week of July 2018 and 2019 right after the onset of the rainy season. The seeds were planted in 40 cm between rows and 10 cm between plants on a plot size of 3.2m *4m where each plots contains 8 rows and total area of the experiment was 620.6m 2 . Spacing between blocks and plots were 1m and 0.5m respectively. The seed rate was 60 kg/ha. A fertilizer 100 kg/ha NPS was applied during seed planting. For estimation of biomass yield only the entire three rows were harvested at 50% of flowering stage and the remaining three rows used for seed yield and haulm yield production.

Data collection and statistical analysis
The varieties were harvested at 50% flowering stage and evaluated for their biomass yield  (1970). The data were subjected to analysis of variance (ANOVA) using Genstat computer software program and significant mean differences were separated using Duncan's multiple range test (DMRT) at 5%.

Dry matter yield and other morphological characteristics of soybean varieties
The combined mean (  Assaeed et al. (2000).
However, the current result was sufficient for support livestock production as the existing environment. The combined analysis of variance over two years at Jari for vigorsity, leafiness score, days to 50% flowering, biomass yield, dry matter yield and plant height at 50% flowering (Table 3) showed that there were highly significance difference (P< 0.  Assaeed et al. (2000).  (2018) because, unfortunately, in this cropping season, there was heavy rain intensity with ice during early stage of growing at Sirinka. The dry matter yield of Pawe-03 was 2.39t/ha lowers than 7.34 t/ha reported by Suzan (2004) and 6.72 t/ha reported by Assaeed et al. (2000). The combined analysis across locations showed that variety Gishama (3.97 t/ha), Gizo (3.60 t/ha), Pawe-03 (4.04 t/ha) and Wogayen (3.36 t/ha) were higher haulm yield as compared to the other soybean varieties. The haulm yield of Pawe-03 (4.04 t/ha) higher than 3.23 t/ha reported by Sisay Belete (2017) but lower than 5.31 t/ha reported by Yagoub et al.(2012).

Seed yield and other agronomic characteristics of soybean varieties
The combined mean (   Assaeed et al. (2000) at Chefa. This indicated that Gishama and korme had highest lignin contents as compared to other varieties.
The crude protein content of variety Wollo 35.56%, 27.66% at Jari and Sirinka respectively was comparatively higher than (Craig et al., 1998) the mean of CP 24.5%, 20.01% reported by Assaeed et al. (2000). Therefore, it possible to generalize that all varieties in all three locations used as protein supplement for growing and lactating animals where soybean varieties can be accessible to producers.

Conclusion and Recommendation
The result indicated that there were significance difference among soybean varieties for dry matter yield, haulm yield, seed yield and other agronomic traits. The varieties in their combined analysis showed that Afgat, Pawe-03 and Wollo gave better in most of important parameters than other varieties. The CP content of all varieties had above the optimal level to use as protein supplement in livestock nutrition. Specifically Wollo and Gizo varieties gave higher crude protein content in three locations than others. The crude protein content of such varieties indicated that these species can be used as supplementary feed for livestock production.
Therefore, Afgat, Pawe-03 and Wollo recommends for the given areas of Jari , Chefa, Sirinka and could be produced in similar environment for the beast of produced optimal amount of dry matter, haulm and seed yield as forage of high quality and good protein supplement for growth and production of ruminant. Thus, further research is needed to investigate on the utilization of livestock and varieties response on production.