class="t m0 x3 h9 y15f ff3 fs6 fc0 sc0 ls0 ws10">straw increased with increasing rate of compost and also
increased with alfalfa pellets at high rates (Tables 7 and
8). In 2010, total N, P, K and S uptake of barley in seed +
straw increased considerably with application of compost
and alfalfa pellets over the zero-amendment control (Ta-
bles 7 and 8). There was also a tendency of increase in
total N, P, K and S uptake in seed + straw of barley
Copyright © 2012 SciRes. OJSS
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305
Table 6. Seed yield and total biomass yield (TBY) of wheat (2008), pea (2009) and barley (2010) with various amendments
applied annually in spring of 2008, 2009 and 2010 at Star City, Saskatchewan (Experiment 2).
Treatment Seed yield (kg·ha1) TBY (kg·ha1)
No. Amendments 2008
wheat
2009
pea
2010
barley
2008
wheat
2009
pea
2010
barley
1 Control (no amendment) 264 668 2233 3237 4893 5005
2 Compost @ 10 Mg·ha1 435 796 3359 3905 5546 7501
3 Compost @ 20 Mg·ha1 470 965 3570 4611 5360 8216
4 Compost @ 30 Mg·ha1 580 1180 3671 5069 6379 8126
5 Wood ash @ 1 Mg·ha1 305 765 2348 3897 4574 4831
6 Wood ash @ 2 Mg·ha1 341 760
2705 3695 5009 5489
7 Wood ash @ 3 Mg·ha1 315 791
2804 3980 5030 6230
8 Alfalfa pellets @ 1 Mg·ha1 377 493
2663 3909 3901 5716
9 Alfalfa pellets @ 2 Mg·ha1 340 585
2872 3837 4565 5863
10 Alfalfa pellets @ 4 Mg·ha1 400 629 3859 4032 4782 8441
11 Alfalfa pellets @ 6 Mg·ha1 429 726 4067 4322 5747 9577
12 Gypsum @ 10 kg·S·ha1 391 758 2110 3855 4421 4540
13 Gypsum @ 20 kg·S·ha1 328 633 2103 3750 4480 4685
16 Control + Penicillium bilaiae 319 691 2128 3635 3635 4638
17 Rock phosphate finely-ground @ 20 kg·P·ha1 271 619 2170 3116 4292 4720
18 Rock phosphate finely-ground @ 20 kg·P·ha1 +
Penicillium bilaiae 317 663 2133 3987 4639 4761
19 Rock phosphate granular @ 20 kg·P·ha1 317 592 2323 3719 4198 5020
20 Rock phosphate granular @ 20 kg·P·ha1 + Penicillium bilaiae347 589 2227 3775 4138 4772
21 MykePro 341 626 2202 4245 4195 4342
LSD0.05 92 221 367 834 903 941
SEMz 32.3*** 77.9*** 129.3*** 294.1* 318.4*** 331.9***
z* and *** refer to significant treatment effects in ANOVA at P 0.05 and P 0.001, respectively.
Table 7. Total N and P uptake in seed + straw of wheat (2008), pea (2009) and barley (2010) with various amendments ap-
plied annually in spring of 2008, 2009 and 2010 at Star City, Saskatchewan (Experiment 2).
Treatment Total N uptake in seed + straw
(kg·N·ha1)
Total P uptake in seed + straw
(kg·P·ha1)
No. Amendments 2008 wheat2009 pea2010 barley 2008 wheat 2009 pea 2010 barley
1 Control (no amendment) 34.6 46.5 57.7 4.6 6.7 13.1
2 Compost @ 10 Mg·ha1 42.0
57.0 76.8 6.3 9.3 19.8
3 Compost @ 20 Mg·ha1 44.0 62.5 84.4 7.9 10.5 22.4
4 Compost @ 30 Mg·ha1 48.8 75.0 89.4 8.9 12.8 23.8
5 Wood ash @ 1 Mg·ha1 38.9 48.9 51.1 5.2 7.3 13.8
6 Wood ash @ 2 Mg·ha1 35.7 52.5 56.9 5.4
8.3 15.0
7 Wood ash @ 3 Mg·ha1 41.7 51.3 64.4
6.0 7.9 16.5
8 Alfalfa pellets @ 1 Mg·ha1 39.2 36.6 63.4 5.0 5.7 15.0
9 Alfalfa pellets @ 2 Mg·ha1 38.1 43.3 66.9 5.7 6.6
15.3
10 Alfalfa pellets @ 4 Mg·ha1 42.7 47.6
94.9 5.4 6.8 19.5
11 Alfalfa pellets @ 6 Mg·ha1 49.4 62.5 114.6 6.6 7.8 21.4
12 Gypsum @ 10 kg·S·ha1 41.1 48.0 55.1 5.7 6.4 12.7
13 Gypsum @ 20 kg·S·ha1 36.0 43.9 53.8 4.8 6.5 13.0
16 Control + Penicillium bilaiae 34.6 40.8 53.1 4.5 5.9 13.1
17 Rock phosphate finely-ground @ 20 kg·P·ha1 29.3 43.7 53.2 4.2 6.9 13.2
18 Rock phosphate finely-ground @ 20 kg·P·ha1 +
Penicillium bilaiae 35.4 45.7 54.7 5.9 8.0 13.9
19 Rock phosphate granular @ 20 kg·P·ha1 31.5 40.4 55.2 5.5 6.9 14.1
20 Rock phosphate granular @ 20 kg·P·ha1 + Penicillium bilaiae 37.5 39.6 52.6 5.4 6.6 13.6
21 MykePro 40.4 43.2 52.4 6.2 7.0 13.1
LSD0.05 8.7 9.6 10.6 1.4 1.5 2.1
SEMz 3.07*** 3.37*** 3.73*** 0.50*** 0.52*** 0.74***
z*** refers to significant treatment effects in ANOVA at P 0.001.
Copyright © 2012 SciRes. OJSS
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306
Table 8. Total K and S uptake in seed + straw of wheat (2008), pea (2009) and barley (2010) with various amendments ap-
plied annually in spring of 2008, 2009 and 2010 at Star City, Saskatchewan (Experiment 2).
Treatment
Total K uptake in seed + straw
(kg·K·ha1)
Total S uptake in seed + straw
(kg·S·ha1)
No. Amendments 2008
wheat
2009
pea
2010
barley
2008
wheat
2009
pea
2010
barley
1 Control (no amendment) 48.0 77.4 40.1 3.1 5.1 5.4
2 Compost @ 10 Mg·ha1 49.5 93.4
71.0 3.9 12.6 7.5
3 Compost @ 20 Mg·ha1 56.0
96.9 89.0 4.7 13.3 8.5
4 Compost @ 30 Mg·ha1
64.2 123.5 88.5 4.8 16.9 8.6
5 Wood ash @ 1 Mg·ha1 56.3 76.5 38.2 4.5 8.5 5.1
6 Wood ash @ 2 Mg·ha1 53.3 87.3 45.2 4.0 10.8 5.9
7 Wood ash @ 3 Mg·ha1 54.1 87.4
54.3 4.8 11.5 6.5
8 Alfalfa pellets @ 1 Mg·ha1 54.0 62.7 48.1 3.7 4.3 5.8
9 Alfalfa pellets @ 2 Mg·ha1 55.3 72.6 49.8 3.4 4.6 5.9
10 Alfalfa pellets @ 4 Mg·ha1 58.6 83.9
79.3 3.9 4.9 8.0
11 Alfalfa pellets @ 6 Mg·ha1 59.9
111.6 109.3 4.4 5.8 9.3
12 Gypsum @ 10 kg·S·ha1 52.2 70.9 39.2 4.1 6.4 5.4
13 Gypsum @ 20 kg·S·ha1 50.3 74.6 38.7 3.9 8.5 5.8
16 Control + Penicillium bilaiae 46.5 55.1 37.3 3.2 3.8 4.8
17 Rock phosphate finely-ground @ 20 kg·P·ha1 37.8 66.1 37.2 2.8 4.7 4.8
18 Rock phosphate finely-ground @ 20 kg·P·ha1+
Penicillium bilaiae 48.0 74.9 41.7 3.2 4.8 5.0
19 Rock phosphate granular @ 20 kg·P·ha1 47.4 66.9 42.9 3.2 4.3 5.1
20 Rock phosphate granular @ 20 kg·P·ha1 + Penicillium bilaiae 50.3 66.4 38.2 3.6 4.8 5.0
21 MykePro 57.5 70.8 36.4 4.0 4.3 4.8
LSD0.05 17.6 18.7 12.0 1.0 2.2 0.9
SEMz 6.22 ns 6.59*** 4.22*** 0.35*** 0.79*** 0.32***
z*** and ns refer to significant treatment effects in ANOVA at P 0.001 and not significant, respectively.
with wood ash. The results suggested that N, P, K and S
in compost and alfalfa pellets became available to the
crop in all three growing seasons. There was no increase
in total N uptake in seed + straw from the application of
other amendments.
3.3. Cereal-pea Intercropping
3.3.1. Experi ment 1 a t Spalding
At Spalding, seed yield was lower with pea alone, but
greater with wheat alone than wheat-pea intercrop in
2008 (Ta ble 9). The order of seed yield was pea alone <
wheat + pea intercrop < wheat alone. The LER for
wheat-pea intercrop was 1.08 (0.62 + 0.46), suggesting
8% less land requirement for wheat-pea intercrop com-
pared to wheat or pea grown as sole crops to produce the
same seed yield. In 2009, barley alone and barley inter-
cropped with pea produced lower seed yield than the pea
alone (Table 9 ). The order of seed yield was pea alone >
barley + pea intercrop > barley alone. The LER for
barley-pea intercrop was 0.96 (0.42 + 0.54), suggesting
slightly higher land requirement for barley-pea intercrop
compared to barley or pea grown as sole crops for the
same seed yield. In 2010, seed yield of pea alone was
highest, followed by barley-pea intercrop, with the lowest
seed yield with barley alone (Table 9). The LER for bar-
ley-pea intercrop was 1.29 (0.73 + 0.56). This suggests
29% lower land requirement for barley-pea intercrop
compared to barley or pea grown as sole crops for the
same seed yield. The total biomass yield of various
crops in all three years usually showed trends similar to
seed yield (Table 9).
3.3.2. Experiment 2 at Star City
At Star City, seed yields were very low due to severe
wild oat infestation in 2008, and the order of seed yield
was pea alone < wheat + pea intercrop = wheat alone
(Table 10). The LER for wheat-pea intercrop was 1.22
(0.68 + 0.54), suggesting 22% less land requirement for
wheat-pea intercrop compared to wheat or pea grown as
Copyright © 2012 SciRes. OJSS
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307
Table 9. Seed yield and total biomass y ield (TBY - seed + straw) of wheat, barley, or pea grown as sole crops and as intercrop
(wheat-pea in 2008, and barley-pea in 2009 and 2010) without addition of any amendment in 2008, 2009 and 2010 at Spalding,
Saskatchewan (Experiment 1).
Year/treatment
Year Treatment number Sole crops versus intercrop Seed yield (kg·ha1) TBY (kg·ha1)
2008 1 Wheat 1902 5930
21
Pea 762 3997
22 Wheat + pea 1532 (1180 + 352) 5191
LSD
0.05 267 690
SEM 77.1*** 199.3**
2009 1 Barley 766 1359
21
Pea 3423 5159
22 Barley + pea 2167 (324 + 1843) 3595
LSD
0.05 431 581
SEM 124.6*** 167.9***
2010 1 Barley 400 1400
21
Pea 1253
4267
22 Barley + pea 990 (293+697) 3018
LSD
0.05 486 1352
SEM 123.7* 344.3*
*, ** and *** refer to significant treatment effects in ANOVA at P 0.10, P 0.05, P 0.01 and P 0.001, respectively.
Table 10. Seed yield and total biomass yield (TBY - seed + straw) of wheat, barley, or pea grown as sole crops and as inter-
crop (wheat-pea in 2008, and barley-pea in 2009 and 2010) without addition of any amendment in 2008, 2009 and 2010 at
Star City, Saskatchewan (Experiment 2).
Year/treatment
Year Treatment number Sole crops versus intercrop Seed yield (kg·ha1) TBY (kg·ha1)
2008 1 Wheat 264 3237
14 Pea 71 3635
15 Wheat + pea 217 (179 + 38) 3829
LSD
0.05 66 836
SEM19.2** 241.7ns
2009 1 Barley 1409 3799
14 Pea 668 4893
15 Barley + pea 886 (389+497) 4372
LSD
0.05 242 1004
SEM69.8*** 290.1
2010 1 Barley 2233 4905
14 Pea 2399 5005
15 Barley + pea 2569 (1234+1335) 4952
LSD
0.05 859 1519
SEM 248.3ns 439 ns
, **, *** and ns refer to significant treatment effects in ANOVA at P 0.10, P 0.01, P 0.001 and not significant, respectively.
Copyright © 2012 SciRes. OJSS
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308
sole crops to produce same seed yield. In 2009, barley
alone produced greater, but barley intercropped with pea
produced lower seed yield than the pea alone control
(Table 10). The order of seed yield was barley alone >
barley + pea intercrop > pea alone. The LER for barley-
pea intercrop was 0.93 (0.35 + 0.58), suggesting slightly
higher land requirement for barley-pea intercrop com-
pared to barley or pea grown as sole crops for the same
seed yield. In 2010, seed yield of barley-pea intercrop
tended to be higher than sole crops of barley and pea
(Table 10). The LER for barley-pea intercrop was 1.11
(0.55 + 0.56). This suggested that barley-pea intercrop
had 11% lower land requirement compared to barley or
pea grown as sole crops for the same seed yield. The
total biomass yield showed trends similar to seed yield
(Table 10).
4. Discussion
Earlier studies have shown potential beneficial effects of
both organic and mineral/inorganic amendments (that are
allowed as nutrient sources for certified organic produ-
ction), and soil activators/inoculants on crop yields, pro-
duce quality and nutrient uptake [7,19-22]. Similarly, in
our study a few amendments improved yield and nutrient
uptake of crops grown on certified organic farms, and the
results are discussed in detail by providing ex- planations
in the following paragraphs.
Previous research has indicated that composted ma-
nure is a good supplier of N, P, K, S, and other nutrients,
and is expected to increase crop yield when these nu-
trients are limiting in soil for optimum crop growth/de-
velopment [23]. Similarly, in our study, composted ma-
nure and alfalfa pellets in many cases and also wood ash
in some cases were effective in increasing crop yields in
2008 and 2010, when cereals were the test crops, and
nutrient uptake in all years regardless of crop type. The
increases in crop yields from various amendments were
most likely by preventing some nutrient deficiencies in
crops, especially N (the most yield limiting nutrient in
soil at our experimental sites), as also suggested for ma-
nure by other researchers [23]. For alfalfa pellets, it is
possible that narrow C:N ratio in plant materials of al-
falfa pellets may have supplied N and other nutrients
after mineralization [24]. In our other previous study for
the same experimental sites on residual effects of amend-
ments on soil properties [13], total and light fraction or-
ganic C and N, Nmin, and available N, P, K or S in soil
usually increased after three annual applications of com-
post, alfalfa pellets, wood ash or gypsum, depending on
the amendment and site. Therefore, the increases in up-
take of N, P, K or S in crops in the present study were
due to the fact that these amendments supplied these nu-
trients for plant uptake, most likely by increasing nutrient
availability in soil due to improvement in soil fertility
and also possibly by enhancing soil quality/tilth/health.
Crops with taproots can absorb nutrients from deeper
soil layers [25], depending on the root length [26]. How-
ever, if the surface and sub-soil layers are low in avail-
able P, then it is very difficult to increase the availability
of P on the farm site and sustain high crop production
under organic farming systems, by using deep taproot
crops in the rotation to bring P from deeper soil layers to
the surface soil for future crop use [5]. So, the only al-
ternative is to add external P source, which is acceptable
and practical under organic farming. For example, pre-
vious research has suggested the use of vesiculararbus-
cular mychorrhiza (VAM), Penicillium b ila iae , rock
phosphate, or bone meal to increase the release of P from
soil and organic P fertilizers/amendments in order to
prevent P deficiency in P-deficient soils and increase
crop yields [19,21-22,27-28]. In a field study in Sas-
katchewan, Takeda [25] did not find any benefit of rock
phosphate application on crop yield and P uptake over
two years at any of the three sites, but showed increases
in crop yield and P uptake at two sites from the applica-
tion of rock phosphate in a combination with Penicillium
bilaiae. Gleddie et al. [29] also reported positive re-
sponses to Penicillium bilaiae inoculation on soils that
were extremely deficient in P for optimum growth. How-
ever, in our study on organic farms, there was no con-
sistent significant beneficial effect of rock phosphate
and/or Penicillium bilaiae on crop yield and P uptake in
our study (with potentially P-deficient soil in Experiment
1) over three years. It is possible that our soils may not
be deficient in available P to the level to limit crop yield
under organic production, because of the possibility of
low yield potential under organic farming, as suggested
by Brandt et al. [23] when comparing organic and con-
ventional cropping systems over 12 years. We expected
increase in crop yield and/or P uptake from the finely
ground rock phosphate, because of the increase in surface
area, but it did not happen. As explained earlier, this
could be due to low yield potential of organic crops, and
possibly the finely ground rock phosphate may have also
conferred physical or chemical changes in soil, which in
turn may have affected the microbiological activities in
soil. This may have resulted in immobilization/fixation
of P from finely ground rock phosphate into the soil or-
ganic fraction and subsequently impacting plant growth
negatively on this potentially low P soil. Thus, suggest-
ing the need of future long-term investigation to deter-
mine the efficacy of rock phosphate, Penicillium bilaiae,
MykePro and other amendments in preventing deficiency
of P in organic crops on soils extremely deficient in
available P for optimum yield.
Like P, if soil is low in available S, then the only al-
Copyright © 2012 SciRes. OJSS
Relative Effectiveness of Various Amendments in Improving Yield and
Nutrient Uptake under Organic Crop Production
309
ternative is to add external S source that can be used un-
der organic farming. Our previous research has suggested
that gypsum can be a suitable source of S to prevent S
deficiency in crops [30]. However, in our present study
on organic farm, there was little effect of gypsum used in
Experiment 2 (with potentially S-deficient soil at this site)
on crop yield and S uptake in any of the three years. It is
possible that our soil may not be deficient in available S
to the extent that can limit crop yield, because of the low
yield potential of crops in our study under organic farm-
ing and also lower S requirements of cereals than oil-
seeds. This suggests the need of future research to deter-
mine the feasibility of gypsum and other amendments
(such as granular elemental S) in preventing S deficiency
in organic crops on soils extremely deficient in available
S for optimum crop growth and yield. In our study, wood
ash increased yield of barley in both experiments in 2010,
and this may be due to the supply of P, S, or other nutria-
ents to the crop, because it contains fairly high content of
available P, S, K, Ca and Mg, but little or no N.
In 2009, there was no beneficial effect on seed yield
and/or nutrient uptake of pea from any amendment in
Experiment 1 (in fact, seed yield and nutrient uptake of
pea decreased with increasing rate of alfalfa pellets in
this experiment), and only from compost application in
Experiment 2. This was most likely that pea can fix N
from the atmospheric air for its own requirement [8,
31-33] and do not need any N (probably the most limit-
ing nutrient in soil at these sites) from external sources.
Thus, suggesting little or no increase in yield of pea from
N-supplying organic amendments, especially when soil is
adequately supplied with P, S, K, or other nutrients and
legume is the main crop. When legumes are grown in the
rotation, it is also possible that their crop residue after
decomposition may also provide N benefit to subsequent
crops for improving yield under organic farming [32,34].
In Experiment 1, we did not expect any dramatic reduc-
tion in seed yield of pea from alfalfa pellets application
treatments compared to the control. The decrease in seed
yield of pea with increasing rate of alfalfa pellets was
most likely due to the increase in wild oat infestation as
evidenced by the significant increase in seed yield of
wild oat with increasing rate of alfalfa pellets (data not
shown; seed yield of wild oat ranged from 122 to 317
kg·ha–1).
Previous research has suggested yield on organic
farms can be increased (also called out-yielding calcu-
lated as LER) by intercropping non-legume and legume
annual crops together compared to as sole crops for ce-
real-legume [10,11]. Similarly, in our study, the LER
values were greater than 1 in the cereal-pea intercrop
treatments compared to the wheat, barley, or pea as sole
crops in 2 of the 3 years. This indicates less land re-
quirement for wheat- or barley-pea intercrop compared to
wheat, barley, or pea grown as sole crops to produce the
same seed yield. This also suggests the importance of
growing intercrops in improving productivity and use
efficiency of land and soil nutrients, while sustaining
high crop production.
5. Conclusion
There was some potential benefit in improving yield and
nutrient uptake of wheat and barley from compost, alfalfa
pellets and possibly wood ash, and from intercropping
non-legume wheat or barley with legume pea. Our find-
ings suggest the need for future research to determine the
feasibility of rock phosphate, Penicillium bilaiae, Myke-
Pro, gypsum or other amendments in preventing P and/or
S deficiency in organic crops using soils extremely defi-
cient in these nutrients.
6. Acknowledgements
The author thanks Western Alfalfa for financial assi-
stance and supplying alfalfa pellets amendment for this
study, International Compost Ltd., Calgary, Alberta, for
supplying Rock Phosphate fertilizers for this study, and
D. Leach and K. Strukoff for technical help.
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