PERUBAHAN BEBERAPA SIFAT FISIKA-MEKANIKA AKIBAT LINTASAN PENGOLAHAN TANAH DENGAN TRAKTOR POROS-DUA PADA BEBERAPA LAHAN MIRING DAN DAMPAKNYA TERHADAP HASIL KEDELAI
ABSTRACT: The research aimed
to investigate how far increasing frequency of tractor traffic tillage on slopy
ground could deteriorate land stability and soil productivity has been carried
out by observing and analyzing the changes of soil physical-mechanical properties
underneath wheel tracks of a 2-WD tractor, at Andisols Order Soil. The
experiment was conducted at the experimental field of Sare, gampoeng Aceh
Village, Sub-province Aceh Besar, Aceh Province, from April up to September
2009. The altitude is 445 m above sea level. Research method employed,
encompassing: (1) variance analysis due to factorial split-plot random design,
to observe the effect of the treatments on soil productivity as indicated by
soybean plant (Gycin max L.). The design consisted of three levels of
treatments of land slope as the main plots, where: k1 = 0 -5 percent
(relatively flat), k2 = 6 -10 percent (rather slopy), dan k3 = 11-15 percent
(slopy/critical), and six levels of treatments of traffic tillage frequency as
split plots, where: l0 = no traffic, l1 = one time traffic, l2 = three times
traffic, l3 = five times traffic, l4 =
seven times traffic, and l5 = nine times traffic, each at two replications,
respectively; and (2) regression and correlation analysis that was used to
observe the relation of traffic tillage
frequency and changes of soil physical-mechanical properties as indications of
land stability and productivity changes. Data observed were: soil bulk density,
total porosity, stability index of soil
aggregates, soil permeability, moisture
content, soil consistency, soil plasticity, soil cne index, soil shear
strength, and land productivity indicated by yield components of soybean plant,
i.e.; root length, root weight, and yield of soybean plant. Results of the
research generally indicated that maximum percentage of soil
physical-mechanical changes occurred in k1 to k3 at l2 was tolerable for its
soil stability index was greater than 30 in which the yield of soybean –
relatively low though, varied at the local level within 0.6-1.9 tonnes a
hectare. Obtained from variance analysis the yield of soybean interacted
significantly at l0-l5 as well as at k1-k3. Quantitatively, the results showed
that the changes of soil
physical-mechanical properties as well as growth components and yield of
soybean were significantly different at increasing frequency of tillage traffic
and land slopes. While qualitatively, obtained from regression-correlation
analysis the above indication showed polynomial relations of a reliability R2
of 0.96 to 1.00 for yield of soybean
plant and stability index of soil aggregates at increasing frequency of traffic
tillage of l0-l5 in the three land
slopes of k1-k3..
Penulis: Yuswar Yunus
Kode Jurnal: jpbiologidd100057
