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UDC 633.162:631.543.2:631.816.11:633.321
THE EFFECT OF COVER CROP SEEDING RATES (SPRING BARLEY) AND MINERAL FERTILIZERS ON THE STATE OF PURPLE CLOVER
Durnev G.I., Petrova S.N., Doctors of Agricultural Sciences Zolotukhin A.I., Candidate of Agricultural Sciences Izmalkova E.Y., Undergraduate Orel State Agrarian University, Orel City, Russia
E-mail: [email protected]
ABSTRACT
The studies were conducted on a dark-grey forest soil with humus content of 4-5% P2O5 -10, K2O - 12 mg/100g. The purple clover was sowed together with barley by a combined grain grass seeder SZT - 3,6. The seeding rate for clover is 15 kg/ha, for barley - 2,5; 3,0 and 4,0 million viable seeds per hectare. The mineral fertilizers were applied under the previous crop. Research results: optimal barley seeding rate with complementary seeding of clover is 3 million seeds/ha against the background of mineral fertilizers N45P50K60.
KEY WORDS
Purple clover; Spring barley; Mineral fertilizers.
The novelty of the research is that in Orel and the neighbor regions the seeding rate of modern varieties of spring barley with rich tillering is not established. According to our observations, with the free location of seeds on the field (a seeding rate is 90-100 kg/ha) the productive barley tillering reached 10-12 seeds per one plant, yet its yield reached 40 cwt/ha. The agricultural workers follow the barley seeding rate of 4 million viable seeds per hectare. However, it isn't always justified and doesn't depend on the purpose of its cultivation - for feed or brewing. Moreover, barley seeding rate is not determined in case when it is a cover crop for perennial herbs, most often purple clover.
MATERIALS AND METHODS OF RESEARCH
The soil is dark grey forest. The humus content is 4,0-4,5%, P2O5 and K2O - 10-12 mg/100 g. The previous crop in all years of studies was buckwheat. The object of the research was purple clover Orlovsky Middle-early, bred in the Orel Research Institute for Agriculture and entered the state register since 1995. The clover belongs to double cutting type. In the first cutting it gives very good seeds in the third decade of August. Its advantage is good yield of forage and seeds, that's why it is more preferable than recommended varieties Early-ripe Orlik and late-ripe Srednerussky for the Orel region. The clover seeding rate is 15 kg/ha. The malting barley Scarlett (Germany) was used as a cover crop.
The experiment has threefold replication, the location of the test plots is systematic. The area of a plot is 35 m2 (7 x 5 m). The experiment was conducted to study the spring barley seeding rates - 2, 3, and 4 million viable seeds per one hectare against the background of mineral fertilizers: without fertilizers (control), N30P50K60, N45P50K60, N60P50K60 and N90P50K60.
Summer 2006 was characterized by abundant rainfall, especially in the second half of vegetation. Summer 2007 differed in lack of moisture and high temperatures. The vegetation period in 2008 was generally favorable both for clover and for barley. In spring 2007, we were unable to prepare the soil for clover seeding properly. As a result, its shoots were so thin that they were not subject to counting. The barley was also too thin and that year its yield ranged from 9 to 25 cwt/ha in the variants of experiment.
The agro technology of the experiment was traditional, adopted in the Orel region for the barley cultivation with complementary seeding of clover. The fall tillage is 20-22 cm deep,
in spring - mulching, fertilizers application, cultivation and barley seeding simultaneously with clover by the combined grain grass seeder SZT-3,6. In the tillering stage, barley crops were treated with a herbicide Bazagran M (4 l/ha). Aktara (0.2 kg/ha) was used as a pesticide. In case of crops diseases they were treated with a fungicide Alto Super (0,5 l/ha). The statistical analysis was done by the method of V.A. Dospekhov (1985).
RESULTS AND THEIR DISCUSSION
It should be noted that for the years of research the average barley yields were rather low, 20-35 cwt/ha (Table 1). It is connected with the fact that in the drought season 2007 due to the lack of moisture the seeds yield reached 13-20 cwt/ha (Table 1). In the wet season 2006, the barley yield in a greater extent was effected by mineral fertilizers, especially nitrogen ones. So, if in the fertilizers free variant when the seeding rate was 2 million seeds per hectare it was 13.6 cwt/ha, then in the variant of N90P50K60 - 35,6 cwt/ha, i.e. 2.6 times higher. When the seeding rate is 3 and 4 million seeds per one hectare - 2.4 times, respectively. In the season 2008, favorable for moisture and warmth, the biggest barley seeds increase was against the background of mineral fertilizers N45P50K60. It reached 3035%. The fertilizer application rate of N60P50K60 was ineffective. Against the background of the clover complementary seeding barley seeds increase practically had no effect on yields, at 2 mln seeds/ha it was even a bit higher.
Table 1 - The effect of rates of seeding, fertilizers and complementary seeding of purple clover on the
barley yield, cwt/ha (2006 and 2008)
Variants of fertilizers Barley seeding rates, mln seeds/ha
2,0 3,0 4,0
Without clover With clover Without clover With clover Without clover With clover
Fertilizers free 19,4 17,1 25,4 20,8 23,2 20,9
N30P50K60 27,1 25,1 28,9 27,0 30,0 30,4
N45P50K60 31,0 26,8 33,4 32,8 33,3 34,3
N60P50K60 32,0 29,7 34,3 33,4 34,2 34,5
N90P50K60 30,9 27,8 33,8 33,6 34,2 34,5
HCP05 - factor A (fertilizers free: 3,1 (2006); 2,7(2007); 2,5 (2008); Factor B (seeding rate): 3,8( 2006); 3,4 (2007); 2,4(2008); Factor C (complementary seeding of purple clover): 2,2 (2006); 2.0 (2008).
In the wet year 2006 the clover under the barley as a cover crop was so mature, that in the fertilizers free variant when the cover crop seeding rate was 2mln seeds per one hectare at the stage of barley getting into ear, it was in the upper layer. Such a state of barley had a negative effect on agricultural yields. Besides, it was difficult to harvest it. Against the increased background of nitrogen fertilizers and the cover crop seeding rate of 3-4 million seeds/ha, at the stage of tilling the clover was in the bottom tier, was a bit thin and didn't produce a negative effect on the barley yield. On the contrary, it contributed to its increase by 10-15%.
The number of active root nodules of leguminous plants in general and clover in particular testifies to their nitrogen-fixing ability. The data in Table 2 show that in the average for 2 years the number of active root nodules was the most in the fertilizers free variants and with low rate of nitrogen fertilizers - N30-45. In the variants with the rate of nitrogen fertilizers N60-90 and with the cover crop seeding rate of 4 mln seeds/ha the number of active root nodules for one plant was 50-60% less than in the fertilizers free variants and with small rates of barley seeding. There were few passive root nodules and their number directly depended upon the number of active ones. The number of clover plants of 100-200 pieces/m2 during its use for two years was considered normal. However, analyzing the average data for 2 years in Table 3, it should be noted that the increase of the fertilizers rates, especially nitrogen, when the cover crop seeding rate is up to 4 mln/ha the density of clover plants reached a critical point - 20-25 pieces/m2. We estimated the clover density and green mass a month after cover crop harvesting, in the third decade of September (Table. 3). The data are presented in the average for 2 years.
Table 2 - The effect of the cover crop seeding and fertilizers rates on the number of active purple clover nodules, seeds per one plant (2006 and 2008)
Variants of fertilizers Barley seeding rates, mln seeds/ha
2,0 3,0 4,0
Fertilizers free 58,0 57,3 48,3
N30P50K60 46,1 47,2 33,9
N45P50K60 43,7 27,2 25,9
N60P50K60 39,1 24,6 23,9
N90P50K60 35,9 28,3 26,0
HCP05 in 2006 9,5 9,5 11,4
HCP05 in 2008 8,6 7,2 8,9
Table 3 - The effect of fertilizers and cover crop seeding rate on the state of purple clover (2006 and 2008)
Variants of fertilizers Barley seeding rates, mln seeds/ha
2,0 3,0 4,0
The state of clover (density and green mass)
pcs/m2 cwt/ha pcs/m2 cwt/ha pcs/m2 cwt/ha
Fertilizers free 156 31,7 126 30,2 114 28,6
N30P50K60 142 28,8 116 28,2 101 26,8
N45P50K60 131 25,7 103 26,7 83 22,5
N60P50K60 120 22,9 93 22,0 80 19,5
N90P50K60 92 21,0 81 18,9 75 17,2
Thus, our studies have shown that with complementary seeding of purple clover under the barley the seeding rate of the latter should not be more than 3 million viable seeds per one hectare. It is better to sow purple clover not simultaneously with a cover crop, but a week later. The matter is that we cannot predict the state of clover in a wet year. The clover is higher than a cover crop, and it makes the cover crop harvest difficult. The most efficient fertilizers rate was - a background of N45P50K60.
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