پديد آورندگان :
خرميان، محمد سازمان تحقيقات آموزش و ترويج كشاورزي - مركز تحقيقات و آموزش كشاورزي و منابع طبيعي صفي آباد - بخش تحقيقات فني و مهندسي كشاورزي، دزفول، ايران , حسنوندي، محمدسعيد سازمان تحقيقات آموزش و ترويج كشاورزي - مركز تحقيقات و آموزش كشاورزي و منابع طبيعي صفي آباد - بخش ثحقيقات چغندر قند، دزفول، ايران , اشرفي زاده، رضا سازمان تحقيقات آموزش و ترويج كشاورزي - مركز تحقيقات و آموزش كشاورزي و منابع طبيعي صفي آباد - بخش تحقيقات فني و مهندسي كشاورزي، دزفول، ايران
كليدواژه :
آبياري سطحي , بي‌خاك‌ورزي , چغندرقند پاييزه , جرم مخصوص ظاهري خاك , شاخص مخروطي
چكيده لاتين :
Introduction: North of Khuzestan province is one of the major areas for autumn sugar beet planting.
Conventional tillage (CT) is widely practiced by sugar beet growers in this region. CT in sugar beet consists of
burning wheat residue, using deep plowing with a moldboard plow or ripper plowing followed by several passes
of disking, leveling, and furrowing. These aggressive tillage practices have many negative consequences for soils.
Losses of soil organic carbon decreases soil permeability and consequently increases soil erosion and surface
runoff. Therefore, applying conservation agriculture principles in sugar beet planting, conservation of residues and
elimination or reduction of tillage, can help to optimize water use management and improve soil health on a farm
scale. The objectives of this study were (i) to determine the possibility of direct planting of autumn sugar beet in
wheat residues, (ii) to estimate sugar beet yield and crop water productivity (WP) under CT, chisel (CH), minimum
tillage (MT) and no-tillage (NT) systems, (iii) to evaluate the response of sugar beet cultivars (Sharif and Palma)
to different soil tillage systems, and (iv) to determine the effect of soil tillage systems on some soil physical
properties.
Materials and Methods: A field experiment was conducted for two years (2016—2017) at the Safiabad Dezful
Agricultural Research Center (32° 14.44´-32°15.93´ and 48° 25.41´-48°47). The soil of the study site was deep,
well-drained with a silty clay loam texture. The mean annual precipitation and evaporation are 317 and 2400 mm,
respectively, with an elevation of 108 m above mean sea level. Irrigation water was supplied from the Dez
irrigation network without any salinity restrictions. The experimental was conducted in a split-plot arrangement
based on a randomized complete block design with three replicates. The main-plot treatment was tillage method
and the subplot treatment was two sugar beet cultivars (Palma and Sharif). Tillage treatments included
conventional tillage (CT) (moldboard ploughing + MT steps), chisel (CH) (chisel ploughing + MT steps),
minimum tillage (MT) (two perpendicular disks, fertilizing centrifugal machine, disking, furrowing, planting with
pneumatic row planter), and no-tillage (NT) (spraying, planting with NT pneumatic row planter). The length and
width of each plot were 100 and 6 m, respectively, and row spacing was 75 cm.
Soil penetration resistance or cone index (CI) readings were recorded in 2 cm increments to a depth of 50 cm
using SP1000 digital penetration tester to reflect the soil compaction. Soil bulk density was determined in 0-10
and 10-20 cm layers. In the first and second year, sugar beet samplings were done 216 and 220 days after planting,
by harvesting a row of 75 cm with length of 10 m (7.5 m2). WP was calculated by dividing the root and sugar yield
to irrigation water and effective rainfall (effective rainfall was calculated every year with SCS method). Composite
data analysis and mean comparison were performed with MSTATC statistical software.
Results and Discussion: Results of CI showed no significant difference between four tillage methods at 0-10
cm depth. With increasing depth up to 30 cm, slight differences in soil compaction were observed for different
tillage treatments, especially in the second year. Overall, compaction in the 0-50 cm profile in the CT and CH
method were about 45% and 33%, respectively, lower than NT method, whereas in MT method it was about 37%
higher than NT method. Results of root branch number analysis showed that the NT and CT treatments had the
lowest branching (2.67 and 2.83, respectively) and the two CH and MT treatments had the highest branching (4.2
and 5.3, respectively). Therefore, NT had no negative effect on root growth of sugar beet. The results of bulk
density measurements in the 0-10 cm layer were consistent with the results of the CI, but at depth of 10-20 cm,
NT method with the highest bulk density (1.71 g cm-3) had significant difference with the other three tillage
methods. Tillage method had no significant effect on root and sugar yield and root and sugar WP. However, in CT
treatment, root yield increased by 6-8.5% and sugar yield by 6-12%, while root and sugar WP in NT treatment was about 8% higher than in the other three tillage treatments. On the other hand, changing climate conditions, especially rainfall during two years of the experiment, resulted in significant interaction between year and cultivar
for yield and WP at 1% probability level. In the first year, the yield of Sharif cultivar (86.7 t ha-1) was higher than
Palma (80.2 t ha-1), but in the second year, despite the decreasing yield of both cultivars, higher resistance of Palma
cultivar to Cercospora disease resulted in a significant increase in sugar yield and WP over last year.
Conclusion: The two-year results of this study showed that the direct planting of autumn sugar beet in wheat
residues (NT) is possible. Sugar beet yield and WP were not significantly different in tillage methods, but NT
reduced tillage traffic from 7 times to 2 times and reduced energy consumption. The response of the two sugar
beet cultivars to different tillage methods was the same and among them the Palma cultivar had the highest yield
because of its higher resistance to Cercospora disease.
