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The International Multiple Cropping Symposium
Studies on Minimum and No Tillages in
Paddy Fields
Shao Dasan, Huang Xixi, Tao Jiayu, Zhuang Hengyang
(Department of Agronomy, Jiangsu Agricultural College)
Studies on Hinirmum and iNo Tillage in Paddy F ields*
Shao Dasan, Huang Xixi, Tao Jiayu, Zhuang Toyn -;.;
(Department of Agronomy, Jiangsu Agricultural
College, Jiangsu Province, the People's Republic
of China)
Minimum and no villages have been studied in the
past few years in this country and have been adopted
widely on many state farms, yielding acma-j good
results. From 1981 to 1984, the experiments were
conducted by us on two faris. This paper deals with
tho effects of ,Iiniuum and no ti.llaes on the energy
requiiments for rice cultivation, the yield and soil
fertility in the southern China warm and rai.-,
weather conditions We attempt to provide some
scientific basis on which a new soil tillage system
with lowor conanptic'n and higher efficien-cy, in
combination of soil use and conservation could be
established.
Methods
One experiment was established fror 1981 to 1983
in Grongqingtuan Far", wh.. re soil be"lo-ng to porrnaeble
Gongqin;gtuan Farm cooperated with us in carrying
out this study, .,; Wargyuan, Xu Jian, Yan Jiurui.
Leng Changhe, Yang JiL.heng and Wang Yixin were
contacted on certain aspects of this study.
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paddy soil, which developed on the deposit in lower
reaches of the Changjiang !liver. Size of tho plots
was 3 mu*. From 1982 to 1984, on the experimental
farm of the college, another one was conducted in
Latin -square design with 3 replications mand the plot
size was 0.3: mu. Table 1 shows some of the physical
and chemical properties of the soils on which the
experiments were conducted.
In both experiments, three tillage practices were
taken as follows.
(1) No tillage -- direct drilling.
(2) Minimumn tillage -- the plots were tilled
to a depth of 5 cm with a.rotary plow.
(5) Conventironal tillage -- the plots were
sloughed to a depth of 14-16 cm, companies with
turnover of soil layers, and then rotated for planting.
In Gongqingtuan Farm, rice was planted with two
.methods, namely direct sowing with a 24-lines seeder
and transplanting by hand. On the college's farm,
only the latter was taken. Rice variety used was
IR661 (IR 24 instead of I1 661 in 1982). In the
direct soved plots, seed rate yias 4 kg/mu, with a
population of about 105 seedlings per mu, and.row
spacing, 25.5 cm. In the transplanting plots, row
spacing was 23.3 cm, and distance between hills,
13.3 cm, with a populatiLon of about 64300 seedlings
per mru. On both farms, 50 kg soybean seed cake,
10 kg urea, 10 kg ammonia phosphate and 7.5 kg
potassium chloride per mu were applied as base
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*. 1 mu = 1/15 ha
fertilizer in ill the .ots. The 'bas fertiliz.'r wmas
spread on the u'rf.ce .sol in the no- tillage 1 lots.
In the inimun and con unti onal-tillagod plots 1i.
soils *were prepared vwi :i the procedure: laughingg (or
not)----ressing rotating. Eosides, to
investigate the effect of different bulk densitie- on
rice growth, pot cultui3 was made.
Results
Rice yields and economic analysis
Rice yields are shc n in table 2. In G-ongqing-
tuas Farn, higher yie ds ieere. gained, in nall plots
under minimum and no illagos, except the direct-sowr,
plots under no tilla.3e in 1983, and somie of the dif-
ferences in the yield weiea significant. On the col-
lege's form, a similar case appeared.
Better economic efficiency was obtainod by minimum
and no villages. With direct sowing, average diesel
oil requiments of 3 years wei'e 1I.08,' 1.45 and 2.18
kg/mu for no, minimum and conventional villages
respectively, anad in comparison uwith conventional
tillage, oil rq-ints jore .oo'asc 6 and b; 65 nc6 3F
for no and minimum tilac:a roseatively. With
translanting, yearl. oil rOquic-nts -. 0.78, 1 .29
and 2.08 kg/mu for no', mining. and conventional til-
lages respectively. The first two tillag-oe decreased
oil roquiments by 631 and 38-? iespect'.vly as c '-'
with the last. Due to docrcaso of "-he costs and
increase of the yield, 1 intiun and no villages resul ed
in significantly h- i or rot Profits than conveOtionai
tillage. 'P profits unier no an. inim1u tillages,
on 3-year avcrna;., were I creased by 25% and 5A,
respectively with direct sowing and by 53% and 33.'
roypectively with transplanting .
W-fect' of the villages on physical properties
of the soils
Pinughin.g could -o '01'.lr rodnco soil bulk density.
v:;nventional tillage decreasedthe bul': density from
1.453 _/ ca "o .0 3', g:/om on the sandy loa-m soil and
from 1.35 g;/A' to 1.00 g/cm on the permpable paddy
soil after ploqgthing. Op the pernea.ble paddy soil,
duo to csollinig clof l.'ys under asume'ging, bulk
duarity continued to deor ate until draining off water
and then turned to increasing. Hcwevr', on the sandy
loan soil, bulk aroni:ty tend1to increase during; the
whole :growth period of rice due to .inking of the
particals of soil.
Suiibnergiug inal..ie.h bulk ,.ansity docrease on the no-
till..aCiud soils and thun, in thy grovintg period of rice,
bulk d;onaities of no-t illa'go.d soils ere not
Significantly higher tann thosi of conventional-til-
Igod soils (only 'by 0,01-0.05 /c".. on the per:eeable
pat.dy soil). The largest di.forc~:-oo in bulk density
b.t,,e;n no an.d c-nventin.nal til.Las or found at 10
day;: after tranplant.ing on the sandy R.;am soil and
at tranplanting on the por.ea'ble paddy anil The
hulk do sitiea of thoe soini: ;u:-tilla Fo.i.s .wer
btwo;on those of no and c ventional-.tilled_ soils.
This pheno :no.n anb's that soil h s ability to adjust
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the bulk density by itself.
Self-adjusted ability of soil to bulk density was
also revealed with pot cultures The soils with dif-
ferent original bulk densities, after harvest, adjust
bulk density to a critical value of 1.3 g/cm On
pot culture, the soils with designed bulk density of .g/cm
(actual density ranging from 1.3 to 1 .5 g/cm3) gave the
highest yield.
In the 2 nd and 3 rd years of the field experiments,
bulk densities of the lower layer (14-30 cm) of the
permeable paddy soil ranged from 1.36 to 1.46 g/cm3
under o tillage and from 1.37 to 1.49 g/cm3 under
conventional tillage-. Bulk densities of the lower
layer of sandy leam sail Tanged from 1.37 to 1.39 g/cm3
under no tillage and from 1.39 to 1.43 g/cm3 under
conventional tillage. Obviously, bulk densities of
the lower layers of both.soils under conventional
tillage were higher than those under no tillage, which
could be caused by the compaction of tillage implements.
If the compaction were reduced or avoided, bulk density
of s0il would not increased.
Penetration resistance of soil corresponded to its
bulk density. The results showed that the penetration
resistances of no and minimum-tillaged plow layer
were higher than those,of .conventiona]-tillaged one
all the time. The differences were even more evident
on the permeable paddy soil. But the differences
became negligible beneath plow pan. It fol-
lows tillages could greatly affect penetration
resistance of soil. The results showed that under no
tillage high bulk density did not give responding
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high penetration resistance, which s specific case
in paddy fields.
Tillages didn't affect markedly the property of
soil ores3 (Table 3). Minimum and no-tillaged soils
had higher structural indexes. as well as larger
proportion of aggregates of 0.25 0.01 mm, but
smaller proportion of the particles of < 0.001 mm in
comparison. with co :nvent ional-tillagcd soils.
which indicated that conventional tillage was
unfavorable for formation -f aggrogates, so that
fineness rose. Coefficients of variation of the capil-
lary po'rosities of no-tillaged soil were the smallest,
which indicated that the p.reo of no-tillaged soils
distributed uniformly, and were stabler both spatially
and temporally. The permeability coofficients (at
1000) of the sandy loam soil at tillering were 5.07
8'a.2' nd 10.32 mmi/day. iJn conventional, minimum and
no-tillaged fields respectively. What is more,
oxidation reduction potential of minimum and no-
tillaged soils were higher than those of conventional-
tillaged soils.
Investigating the profiles of the. soils after
harvest we found that in no-tillagod lots, .the soils
were loosen and rusty-spoteod, while in conventional-
tillagod plots, the acils woere blue-greoy cooured. and
soft, of higher.moistLure contents. Even on the
sandy loan soil, secondary gleization. took place.
Obviously, conventional tillage damaged soil structure,
resulting in puddled soil.
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Effects of th.e illaes on soil nutrients
Two years after no tillago, oYDanic matter content
of top layer increased mnarkedly, (.ad the contents of
total nitrogen, available nitrogen, phosphor us and
potassiuL responsively increasedd. Thu.gh hydrozablo
nitrogen content decreased in i"sub-,plw l'-yer, ?.vaila~ble
phosphorus and potassium contents inorc5nod. On
contrary, in the conventional-tMllgod plots, contents
of- total nitrogen and organic matter no. plow layer did
not decrease, but ones of available nitrogen,
phosphorus and potassium droned.
SEffects of tho tillag';es on growth of the roots
Investigating soil profile for 3 yors: revealed
that rice roots in the nioimum and no-tilloaed plots
were characterized by white colour, deeoor development,
higher rate of bled:ing 'and greater ability to oxide
A, -RA, which were the characteristics of .nre vital
rootQ, and that even nt harveos, toh ending parts of
the roots still remained white-coloured. Proportions
of the roots in .loer layor (14-3f0 cn) to total root
weight ora largerT ,ndr mniimumi and no tillagos than
under conventional tillage, The ro.porti:ns, on the
caudy loam soil, were 11.62%, 10.92% nd 9.44% under no,
i:LniL;,i" and' conventional tillages respectively and on
the perL-anle paddy oil, 7.92, c.475 and 51
roapectively. Testing at tillering with a spring ;
balance. we found thi ...e piLrnts "ere resistant to
being pulled and when pulled up, they carried more
soil on thoir roots (Table 4).
Effects of thoetillages on -growth of rice plants
Fertile soil remained in upper part of plow layer
under no tillage, while conventional tillage turned
over soil layers. On the other hand in minimum and
no-tillaged plots, rice seedlings could be traihsplante,
shallowly as well as at a uniform depth. Thus, in
minimum and no-tillaged plots, rice grew more
prosperously at early tillering stage, hence more
tillers. Then, rice plants in the minimum and no-
tillaged plots turned to steady growth, while in the
conventional-tillaged plots, to prosperous g-rowth
Numbers of.the effective tillers,' on the permeable
paddy soil, were 2.06 x 105, 2.13 x 105 and 2.22 x 105
per mu in the conventional, -minimum and no-tillaged
plots respectively and were 46.8w, 64.8% and 65.85 of
the maximula numbers of the tillers respectively
The results showed that the percentages of the ef-
fective tillers were higher in the minimum and nc-
tillaged plots on both soils. Moderate populations of
rice plants with strong individuals and the. patternn.f
closer distribution of the. ptants were formed in
minimum and no-tillaged plots, while large populations
with weak individuals were formed in the conventiona!'-
t'llaged plots. As a result, the percentages af-in-
fedted hills and dafccted tillers and indexes of
disease infection under minimum and: no villages were
lower than those under conventional tillage. Amounts
of dry matter of rice plants in no-tillaged plots
increased by 18.7%, 19.5% and 11.6% at tillering,
heading and ripening stages respectively in comparison
with conventional-tillaged plots. Accumulation of
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dry matter of rice was related to the density and
pattern of rice plants as well as the spatial
distribution of the leaves, especially the length of
the 4th and. 5th leaves from the top. This agrees with
Ling Qihong, who reported that thetpercentage of filled
spikelbts of rice was negatively correlated with the
total length of the 41?h and 5th leaves from the top.
Weed seeds largely concentrated ac the. top of soil
under minimum and no tillages. Therefore, in the early
growing period, weed control problems were serious,
and especially in the year after minimum and no til-
lages infestation of weeds such as Echinochloa
trusgalli (L.) Beauv. ,Polygonum hydropiper L. and
Leptochloa chinenisis (L.) Ness was very severe.
however, infestation of weeds, except E. Crusgalli4
%ecame light in the 3rd year of no -tillage.
Discussion
The experiments show that soft condition produced
by conventional tillage practices is temporary. If
it is not disturbed mechanically, soil can change its
physical properties in line with environmental
conditions, due to swelling and strinkage. of soil
colloids, as well as effects of root system and
small animals in soil. Cultivated crops, such as rice,
wheat and cotton, not only can adapt to the natural
changes of soil under minimum and no tillages, but
can improve their environments as well. That is why
minimum qnd no tillages result in high yields.
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The highest rice yield was gained on the soil with
density of 1. -1 .4 g/cm both in pot culture and in
field oxperi 'nits. It follows that soil bulk density
under no til' ge is favourable for gowth of rice and
increase of :e yield. This agrees with Ghildyal
(1978), who :tod that soil compaction to some extent
could increase rice yield. Because the bulk density
increases, co, centss o:f tihe nutrients in unit of soil
volume increat correspondingly. On the other hand,
soil with high :. bulk density is favourable for the
movement (f so-' nutrients. Thus, it can be seen that
higher bulk density is favourable for the absorption
of the roots to mineral nutrition. The mechanical
impodance of submerged soil could not affect the
penetration .of -rice roots. Thus, to disturb soil is
undesirable, and. eve4 harmful.
Minimum and no tillages can maintain natural soil
structure, not changlngtthe distribution of soil
pores and the root system of previous crop. As a
result, a vertically continuous pore system; which
plays an important rule in keeping the soil permeable
to air, and coordinating the soil fertility factors
such as water and air,can be formed. The pore system
*formed are.relatively stable both spatially and
temporally, which can resist unfavorable environment
and stabilize soil fertility. Similar conclusion ias
made by Lou Chrnghou, in contrast with no tillage,
conventional tMillage turns cer organic manure, and
,he'n puCddles the flooded soil. It d riagcs soil
structure and reduces x. idatin reduction potential
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of soil. Thus, its effects are incompatible with the
development of soil fertility. Prihar (1982) pointed
out that ploughing could lower the stability of soil
structure and result in unfavourable.distribution of
soil pores. Under natural conditions, the porosity and
contents of soil nutrients are higher in the upper
layer than in lower layer. This pattern is in line
with the requiments of rice growth to nutrients. Vat,
conventional tillage operations, especially rotating
and harrowing under submerging can seriously damage
soil structure. Ploughing and harrowing under not
submerging, if necessary, should be adopted. Of
course, in terraced fields in hill regions and on sandy
soil, in order to prevent water from leakage, the
situation may be different.
Strong and vital roots of rice under minimum and
no tillages were problely due to higher oxidation-
reduction potential and air permeability of soil.
Ratio of the amount of the roots in the layer beneath
plow pan (14-30 cm) to the total amount of roots,
under minimum and no tillages was much higher than under
conventional tillage. That shows deeper development
of rice.roots on minimum and no-tillaged soil. Conse-
quently, the roots can improve the structure of plow
pan, and make full use of the nutrients in lower layer
of soil, favouring high yield. The experiments showed
that rice yield was significantly correlated with the
amount of the roots in lower layer of soil and the
coefficients of correlation were 0.9152 and 0.9471 in
1982 and 1983 respectively. Kawa Ta also reported
that rice yield was significantly correlated with the
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amount of the roots in upper layer of soil in the
fields where rice yields were below 500 lg per mu
(r = 0.831),whilo in the fields where the yields were
over 500 kg per mu, the correlation was not
significant ( r = 0.313). This result shows that in
order to obtain over 500 kg rice-yield-per mu, the
amount of the roots growing down to deeper layer must
be increased. It follows the distribution of the
roots under minimum and no tillages favours high
yield of rice.
Distribution of soil fertility under minimum and
no-tillages is in line with the requiments of rice
growth to nutrients. Under this condition, rice
plants grow prosperously at early stage of tillering,
and then turn to steady growth, so that a moderate
popution with closer distribution of the plants
develops. Minimum and no tillages have some benefits
to increasing rice yield in several aspects, (1)
Prosperous growth at early stage of tillering results-
in higher leaf area index, intercepting more light;
Steady growth in the mid period, makes the leaves
erect, favouring full use of light by the canopy; In
late period, vital roots of rice prolong the functions
of the top leaves, raising light use efficiency,
with more accumulation of the dry matter. (2) Well-
ventilated canopy, lower field moisture and moderate
C/N ratio in rice plants favour disease-resistance
of rice. (3) Percentage of filled spikelets can be
raised.
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Abstract
The experiments in 3 years gave positive results
both on permeable paddy soil and on ..iwady/ loom soil as
the grain yield was concerned
Minimnum and no tillages, not disturbing soil layers,
maintain stable soil structur'o which plays, nn important
rule in resisting unfavorable environments, stabilizing
and coordinating the fertility factors of the soil.
So that, the techniques are favourable f-r proaperus
growth at early stage of tillering and then, steady
growth.
The tillage operations, plow, harrow and leveling
the flooded field, for example, can seriously damage
the natural structure of paddy coil and make it pud-
dling, As a result, rice yield is decreased as well.
Based on the cropping system, a new coil tillage
system, in which various tillage practices are combined
organically, shcud be established, with lower
consumption, higher efficiency, reasonable ecological
cycles and the combination of soil use and conservation.
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Table 1 The main components of the soils tested
Soil
Permeable
:paddy soil
Sandy
loam soil
physicall
clay
<0.01 mm
(f)
83.66
9.9
Clay
<0.01
mm
MM
31.91
(0).
1. 32
1.20
Total
-N
(0)
0'. 102
0.052
Hydroly-'
zsble-N
(ppm)
80 ,9
Alkali-
decompo- I
zable-N
(ppm)
84.0
ILVa i Ji~-
b~e-P
(ppr.i)
5.0
299 .1
CE0
(Me/
lOOg
sol)
16.21
Availa-
ble K
(ppm)
51.0
254.7
Table 3 The influence of tillage methods on soil porosity
Sandy loam soil Permeable paddy soil
Tillage Depth Total Non- Effec- Porosity Total Non-. Effeo- .T-osalty
method (cm) porosity capil- ive at PP2 porosity capil- tive at pF2
lary porosi- .lary porosity2
() Poosil- ty porosi-
S tyty
,(%) (%) ______ _______
No 0-7 46.51 2.40 29.63 13.3 54.10 2.45 24.22 12.72
tillage 0-14 48.97 2.24 27.22 13.9 50i64 2.67 17.20 9.10
Minimum 0-7 48-04 1.20 27.23 12.8 51.06 0.88 21.04 10.86
tillage 0-14 47.19 2.15 28.31 1,0.6 48.43 2.62 15.00. 7.50
Conventional 0-7 48.42 0.62 25.73 12.2 51.86 0.93 22.80 12.82
tillage 7-14 47.25 0.82 24.30 10.6 50.08 0.89 17.20 8.47
Effects of different, tillage methcds on the activity
of rice root system
Si Bleeding Ox.ded
Number W; ofA iamter Perceitage Water (Cg/.ti- (-INiA
s Tilag .of1 aoots roots of root of i'hite. content-! i.o ) (mg/hg fresh
Soil ,:',
method per I (mm) cour in root |__vt_
ant pnt oots 182 1983 182 19
I( ) I -) C%) t I.
--- --- --_3-_ --- --i_--_- ---__--1-.________ -C-. --__
tillage
o on vent ~n~zd
ti1~ e
Wo
4.* 11
L1J.LL~o
176.3
137.2
1347 2
.1 :2
0.992
9.92
0. W-
0.82
0.82
o.E85
0.79
0.83
44.6
45.3
t~,y
~14. *
92.1
I -I.-
38.2
21.4
91.5
89.4
K' 64.1
61.9
54.65
71.0
72.,0
69.9
60. 4
9.8,0
42.T
45.4
40 2
61.5
62.7
60.4
53.8
65.6
Hinimum 1-424.5 0.70 -- 0.80 2Q- 8-T3 J-71.6 61.8 57.7' 51.6
tillage
Conventional
tilltago
97.0
0.57
0.75
14.6
60.5
52o.0
57.33
57.8
Table 4
Sandy
loam
soil
Pe:.'mea-
ble
paddy
soil1
-L-
..... t lk
. -4
I
Table 2 Rice yields and components under three villages
-4 V 4 4
Soil Locality
y Planting
Year method
Tillage
[practice
I I 4
1981
Direct
sowing
planting
No. of
panicles
Per mu
(104)
25.61
25.21
26,14
21.16
20.12
20.28
Filled IPercent-
spikelets age of
Per filled
-panicle spikelets
74.91
78.72
63.15
95.80
100.40
91.80
80,00
85.05
73.70
85.30
82.09
78.63
1000- Grain
grain Iyield
weight (kg/
(g) imu)
27.20
27.28
27.00
26.31
26.31
27.15
498.0
508.0
409.5
512,0
488.0
477.0
Direct N 23.00 60.40 86.30 27.21 344.0 ab
l M 22.70 61.30 85.10 26.99 593.1 a
]sowing
1982 C 25.00 51.60 78.00 28.66 343.4 b
Trans- N 20.60 81.00 86.00 27.11 428.0 a
l i M 17.80 83.00 86.50 27.66 373.6 b
C 20.00 68.70 82.00 28.81 369.2 b
1985
Direct
sowing
Trans-
planting
21.25
22.00
22.41
92.21
90.18
86.85
1 4- 1.
22.19
21.26
20.60
98.96
106.14
104,00
75.25
80.63
66,40
85.75
88.42
81.96
26.75
27.31
26.98
25.28
24.73
25.28
504.0
517.6
518.4
530.8
533.1
505.8
7 I I 4 4 4 4 -.
1982
Trans-
planting
27.07
27.02
26.23
67.98
69.35
72.23
90.80
90.70
89.80
28.86
28.97
28.55
499.6
499.5
498.5
Trans- N 24.10 121.80 91.80 25.14 703.1 a
1983 IM 23.36 123.86 91.38 25.22 697.6 a
plan15 119.27 90.19 2ing
C 23.15 119.27 90.19 25.21 691.1 a
1984
Trans-
planting
22.64
21.36
21.47
90.97
102.33
100.7.1
85.16
85.83
84.52
25.93 505.5
26.95 550.6
26.97 556.9
* i'S = No tillage, M =-.Minimum tillage and C = Conventional tillage.
** Yields with identical letters are not different at p < 0.05.
Signi-
fican-
ce
a
a
a
a
a
. . ,- I I
Trans-
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