Effects of Different Stubble Heights and Number of Harvesting on Yield
and Quality of Oat Hay
Introduction
(Giriş)
One of the most fundamental problems of animal husbandry in our country is that it is
not possible to produce adequate quality roughage. Problems such as pasture and meadow
fields, which are included in qualified roughage sources, are not used under management
principles, and cultivation areas of forage plants are not sufficient, necessitates the provision of
different roughage sources to farmers. Among these, the hays of cereals such as oat and
harvesting pastures created with them have a prominent place. Cereals are widely used in the
world because of their high energy, vitamin, and mineral content (Ensminger et.al, 1990;
Karabulut and Filya, 2007). About 50% of the energy needed by humans is derived from cereals
and 20% from animal products (Kün, 1988). In pastures formed with cereals, plants developed
rapidly in the spring, compared to natural pasture, can reach the maturity of grazing about one
month ago (Gökkuş and Hakyemez, 2001). In addition to having adequate nutrient content of
oat hays, in order to be a cool climate plant, it develops during the cold periods and constitutes
an essential source of roughage in winter and early spring (Bilal et.al., 2015). However, in the
use of oats for roughage and harvesting, the yield and quality of the hay vary depending on the
period of development where the plant is harvested and the height of the stubble to be left.
Stubble height to be left in the harvesting is effective on many factors such as; the plant's
capacity to cultivating and harvesting again (Altın et.al., 2005).
Therefore, this study was carried out in order to determine the effect of the number of
harvestings and the stubble height to be left on the yield and quality of oat hays in the use of
cereals as an alternative coarse fodder source.
Material and Method
(Materyal ve Metod)
The investigation was conducted in the testing ground of Dardanos campus of
Çanakkale University in the years 2014-15 and 2015-16. The mean monthly temperature was
found to be 16,4oC in the first year and 17,8oC in the second year, compared to many years
(15,4oC) during the period in which the experiment was conducted. In the first year, total
precipitation (726.6 mm) was above the average (670.2 mm) for many years, and the second
year (650.1 mm) was below the average. Testing ground soils have clay-loamy structure and
are medium-calcified structures. These soils are inadequate in terms of nitrogen and phosphorus
and are sufficient in terms of potassium. Besides, organic matter is inadequate.
The Kahraman type of Oats was used as plant material. The experiments were
established in a randomized complete block design with three replications. In the experiment,
the parcel width was arranged as 1 m, parcel length as 5 m, total parcel area as 5 m 2, between
parcels as 0.5 m and between blocks as 1 m. The number of harvesting (1, 2, 3, 4 and five
harvest) and the stubble heights (5, 7.5, 10, 12.5 and 15 cm) were considered as factors in the
study. Harvests were made when the plants matured for grazing (20-25 cm in actual height)
(Henning ve ark., 2000).In the experiment, 20 kg/da (diammonium phosphate) was fertilized,
weeds were eradicated by hand and irrigation was not done. Hay harvesting was carried out in
April and May. In this study, oat hay yield analysis and oat hays' HP and HK analyses were
carried out with AOAC (1990). Crude cellulose made according to the methods proposed by
Van Soest et al. (1991). In the statistical analysis of the data obtained from the experiment, JMP
11 statistical package program was used.
Research Findings and Discussion
(Araştırma Bulguları ve Tartışma)
Green Forage Yield
According to the stubble height and the number of harvesting and interactions between
them, green forage yields have changed significantly. With the increase in the remaining stubble
height, green forage yields have decreased, depending on the total and mean of the harvests.
Due to the increase in the number of harvestings, there were significant decreases in green
forage yields. The highest green forage yield (428.4 kg/da) was determined in parcels that were
once harvested with 5 cm stubble, according to the interaction between the stubble height and
the number of harvestings. On the other hand, the minimum yield (110.7 kg/da) was determined
in the parcels, which were harvested five times with 12,5 cm height (Table 1).
Dried Forage Yield (Hay)
The stubble height and the number of harvestings had a significant effect on the mean
dry forage yield for two years. As stubble height and number of harvestings increased, oats, dry
forage yields decreased (Table 2). Green and dry haymaking of oats have decreased
significantly due to the increase in the number of harvestings and the stubble heights. During a
period of growth, in plants that can be made more than one harvesting, generally, depending on
the number of harvestings, there is a decrease in the yield of forage in each harvest (Baytekin
and Gül, 2009). This is due to the physiological structure of the plant as well as variations in
environmental factors. Since plants have a longer growth process in the first harvest time, they
have the opportunity to do more photosynthesis and therefore produce more dry matter until
they reach their maturity. However, in later harvest times, due to the increase in air
temperatures, they develop faster and reach their maturity in a shorter period. However, they
produce less dry matter than the first harvest times, because they can not find the opportunity
of creating photosynthesis tissue. As a matter of fact, in a similar study conducted with barley,
it was noted that the average yield of hay obtained from each harvest decreased due to the
increase in the number of harvestings (Gökkuş et.al, 2017). In the harvest-time, when plants
have sufficient photosynthesis tissue and replacement nutrients, they produce more rapidly after
the harvesting by exhibiting a faster development (Fuller and Tippo, 1954; Manga, 1971). In
contrast, the increase in the amount of stubble after the harvest is also caused by the decrease
in the amount of hay obtained in each harvest, which is less than the total amount of hay
produced.
Crude Protein Content
Crude protein values were significant according to the number of harvestings, whereas
stubble height and the interactions between them were found to be insignificant. The highest
crude protein content (17.4% and 16.4%) of oat hays harvested two and three times during the
growth process, while the raw protein content of the five times harvested parcels of hays was
the lowest with 13.7%. The mean crude protein values were between 15.0-16.3%, depending
on the stubble heights (Table 3). In plants, depending on the development of maturation, the
increase in the cell wall matters in the plant also leads to a decrease in the rate of the crude
protein (Haddi et.al, 2003; Kaya, 2008; Aydoğan et.al, 2014). The most protein content in plants
is at the beginning of the growth in which they are juvenile. At the beginning of growth, plants
have more cells that are divided, so physiological activities in these cells are at the highest level
(Taiz and Zeiger, 2008). Biochemical reactions occur in catalysis of enzymes. Enzymes are
built up of proteins. Therefore, the protein content at the beginning of plants growth is always
high (Gökkuş et.al., 2011). Therefore, as the number of harvestings increases, plant maturation
has also progressed, and the crude protein ratio of hay has decreased. Depending on the height
of the stubble, the absence of significant differences in the crude protein content of the hay may
be associated with the absence of significant differences in the vertical direction of the plant
within the protein content.
Crude Ash Ratio
The crude ash ratio of oat hay has decreased significantly with the increase in the
number of harvestings and stubble heights. However, according to the interaction between the
number of harvestings and stubble heights, the crude ash content of oats did not change
significantly. Crude ash ratios have also decreased regularly with the increase in the number of
harvestings. The crude ash ratio, which was 13.0% in one-time harvesting, was determined as
9.4% in harvestings made 5 times (Table 4). Most of the mineral elements are observed in
protoplasm, where physiological activities are concentrated, and less on the cell wall (Spears,
1994). With the progress of growth, as the ratio of whole organic matter to mineral matter
increases due to the increase of the cell wall compounds in plants, the crude ash ratio of oat hay
and growth also decreases. Therefore, with the increase in the number of harvestings, a decrease
in the number of mineral elements was recorded. A total of 18 elements in pasture cultivars in
the same region were examined in the study (Gökkuş et al. (2012)), it supports this view that
most of the elements are at higher levels in the spring months. On the other hand, the reduction
in crude ash proportions of plants harvested so that they will remain high stubble height to be
left can be explained by the reduction of mineral elements relative to the result of rapid organic
material produced in the upper parts of the plant.
Crude Cellulose Ratio
In the two-year mean, the increase in the number of harvestings and the increase in the
crude cellulose ratio of oat hay were recorded, while the stubble height had no significant
impact. The lowest crude cellulose content was determined in the least number of harvestings
(one-time harvesting with 26.7%), and the highest content was determined in the parcels which
were harvested five times with 33.1%. According to the stubble height, the crude cellulose ratio
of oat hay was between 30.4-31.0% (Table 5). Generally, there were increases in the crude
cellulose ratio of oat hay due to the increase in stubble heights and the number of harvestings.
With the increase in the number of harvestings, growth in plants proceeded, and maturation has
started. At the beginning of growth, most of the protoplasm contents of plants consist of water,
and the cell wall materials are at the lowest level. With the progression of growth and
maturation, the cell wall components are increasing. Besides, with the progress of maturation
in plants, decreases in leaf and stem rates are occurring (Frost et al. 2008). Also, since the stem
ratio, which is the source of the fibrous structure, increases, there are also increases in the cell
wall materials (prude cellulose, NDF, ADF).
Results and Suggestions
(Sonuç ve Öneriler)
This study was carried out in Çanakkale between 2014 and 2016 in order to determine
the differences in the yield and quality of hay according to different stubble height and number
of harvestings in oats. According to the results obtained from the research; hay yield of oats
decreased due to an increase in stubble height and number of harvestings. The highest yields
are obtained from the harvestings made with 5 cm stubble height. The crude protein content of
hay has only changed significantly according to the number of harvestings. The highest protein
ratio (17.4%) was determined in 2-time harvested parcels and the lowest protein ratio was
determined in 5-time harvested parcels. Depending on the increase in harvesting numbers and
stubble heights, the crude ash content of oat hay has decreased. The highest crude ash ratios
(12.5% and 12.3%) were determined in parcels harvested of 5 and 7.5 cm height and parcels of
harvested one time (13.0%). The ratio of crude cellulose has increased due to the increase in
the number of harvestings. The highest cell wall materials have been detected in the harvestings
done 5 times. The lowest rates were determined in applications that were harvested one time.
As a result of the results obtained from the study, it is recommended that the oat hay should be
harvested once, with 5 or 10 cm stubble height, given the yield and quality of the plant, in the
cultivation of roughage.