*3.3.1. Experiment 1. Reduced and zero tillage, with or without fertilisation*

The main effect of treatment on plant number (PN) was highly significant (P<0.01) in all sea‐ sons. The linear effect of week after planting was highly significant (P<0.01) on PN in the winter season of 1991-92 and the rainy season of 1992, but it was not significant (P>0.05) in the dry season of 1992 (Table 6). There was no significant treatment x week interaction on PN in any season. The main effects of treatment and week after planting and its interaction were highly significant (P<0.01) on COV, except for the interaction in the rainy season. Weeks to reach 50% cover were 21, for T2 (winter season) and T4 (dry season); and 20, for T1 and T4 in the rainy season (Table 7).


P≤0.0001.

**Table 6.** Effect of treatments on the number of plants of *Arachis pintoi* CIAT 17434 (pl/m2) by season (Mean ± standard error), according to the tillage by fertilisation combination in experiment 1.


**Figure 4.** Effect of time after planting (4, 8 and 12 weeks) on *A*. *pintoi* CIAT 17434 plant number (PN, number/m2),

Soil Management for the Establishment of the Forage Legume Arachis pintoi as a Mean to Improve Soil Fertility...

**Plant height (cm)**

**vegetation control Vegetation control Burning**

**Table 8.** Combined effect of vegetation control x burning treatments upon *A. pintoi* CIAT 17434 mean plant height

The averages of percentage of seed germination at 7 days on the laboratory were of 44.8±4.08, 44.8±4.45 and 32.8±1.50, for CIAT 17434, CIAT 18744 and CIAT 18748, respective‐ ly; and values (percentages) of emergence at 7 days after planting were 91.3±1.5, 82.0±2.4 and 73.8±1.4, respectively, which were statistically different among them (P<0.05). The main effects of month of planting and accession were significant (P<0.05) on COV. Legume cover increased linearly with time (4, 8 and 12 weeks), but without differences in slope among ac‐ cessions (Figure 5). Using the regression equations of cover *vs.* time, it was calculated that

**Statistical significance of the nonburning vs burning comparison within**

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59

0.01

0.05

plant height (PH, cm) and legume cover (COV, %). The vertical lines are the standard deviations.

*3.3.3. Experiment 3. Establishment of three A. pintoi accessions using seed pods*

Herbicide Without 14.54 ± 1.14

Herbicide With 21.01 ± 1.57 Slashing Without 20.89 ± 1.23

Slashing With 17.09 ± 1.25

**Treatments**

(PHT, cm).

**Table 7.** Mean ± standard error for weeks to reach 50% cover by *A. pintoi* CIAT 17434 according to the tillage by fertilisation combination in experiment 1.

#### *3.3.2. Experiment 2. Control of native pasture growth, with or without P fertiliser*

The effect of time after planting was highly significant (P<0.01) upon all response variables. Height values increased with time, but to a different degree on each main plot combination. The increase in plant height (PH) with time was much larger than the increases with time shown by the other two response variables. The standard deviations were high in all cases and increased with time also (Figure 4). The coefficients of variation remained relatively uni‐ form through time: 28% to 31% for plant number (PN), 29% to 35% for plant height, and 75% to 83% for cover (COV).

When herbicide was applied, the burned plots produced taller plants than the non-burned ones (P= 0.01), but the contrary happened on slashed plots (P<0.05) (Table 8).

P fertilisation did not increase (P>0.05) legume cover in any vegetation control by burning combination. Slashing without burning and without fertiliser, the treatment with the least external inputs, had significantly (P<0.05) less legume cover than the herbicide plus burning plus fertilisation treatment, the treatment requiring the most external inputs (Table 9).

Soil Management for the Establishment of the Forage Legume Arachis pintoi as a Mean to Improve Soil Fertility... http://dx.doi.org/10.5772/53318 59

**Treatments Season**

T1: Reduced With 1.36b ± 0.06 0.78a

standard error), according to the tillage by fertilisation combination in experiment 1.

T3 Zero With 0.81c

T4 Zero Without 0.82c

P≤0.0001.

58 Soil Fertility

P≤0.01.

fertilisation combination in experiment 1.

to 83% for cover (COV).

**Tillage Fertilisation Winter Dry Rainy**

T2 Reduced Without 1.70a ± 0.09 0.73ab ± 0.07 2.56 a ± 0.22

Effect of week after planting: 1.16\*\* ± 0.04 0.68NS ± 0.02 1.72\*\* ± 0.10

**Tillage Fertilisation Winter Dry Rainy**

T1 Reduced With 22 ± 0.4 25 ± 0.8 20 ± 0.3 T2 Reduced Without 21 ± 0.3 24 ± 0.7 21 ± 0.5 T3 Zero With 23 ± 0.4 23 ± 0.5 21 ± 0.4 T4 Zero Without 24 ± 0.3 21 ± 0.6 20 ± 0.2

**Table 7.** Mean ± standard error for weeks to reach 50% cover by *A. pintoi* CIAT 17434 according to the tillage by

The effect of time after planting was highly significant (P<0.01) upon all response variables. Height values increased with time, but to a different degree on each main plot combination. The increase in plant height (PH) with time was much larger than the increases with time shown by the other two response variables. The standard deviations were high in all cases and increased with time also (Figure 4). The coefficients of variation remained relatively uni‐ form through time: 28% to 31% for plant number (PN), 29% to 35% for plant height, and 75%

When herbicide was applied, the burned plots produced taller plants than the non-burned

P fertilisation did not increase (P>0.05) legume cover in any vegetation control by burning combination. Slashing without burning and without fertiliser, the treatment with the least external inputs, had significantly (P<0.05) less legume cover than the herbicide plus burning plus fertilisation treatment, the treatment requiring the most external inputs (Table 9).

*3.3.2. Experiment 2. Control of native pasture growth, with or without P fertiliser*

ones (P= 0.01), but the contrary happened on slashed plots (P<0.05) (Table 8).

**Table 6.** Effect of treatments on the number of plants of *Arachis pintoi* CIAT 17434 (pl/m2) by season (Mean ±

**Treatments Season**

± 0.06 2.56 a ± 0.17

± 0.03 0.60b ± 0.02 0.96 b ± 0.09

± 0.04 0.59b ± 0.03 0.80 b ± 0.07

**Figure 4.** Effect of time after planting (4, 8 and 12 weeks) on *A*. *pintoi* CIAT 17434 plant number (PN, number/m2), plant height (PH, cm) and legume cover (COV, %). The vertical lines are the standard deviations.


**Table 8.** Combined effect of vegetation control x burning treatments upon *A. pintoi* CIAT 17434 mean plant height (PHT, cm).

#### *3.3.3. Experiment 3. Establishment of three A. pintoi accessions using seed pods*

The averages of percentage of seed germination at 7 days on the laboratory were of 44.8±4.08, 44.8±4.45 and 32.8±1.50, for CIAT 17434, CIAT 18744 and CIAT 18748, respective‐ ly; and values (percentages) of emergence at 7 days after planting were 91.3±1.5, 82.0±2.4 and 73.8±1.4, respectively, which were statistically different among them (P<0.05). The main effects of month of planting and accession were significant (P<0.05) on COV. Legume cover increased linearly with time (4, 8 and 12 weeks), but without differences in slope among ac‐ cessions (Figure 5). Using the regression equations of cover *vs.* time, it was calculated that for the August planting it took 45, 46 and 56 days for accessions CIAT 17434, CIAT 18744 and CIAT 18748, to cover 5% of the soil, respectively. Values for September were 55, 50 and 55 days. Plant height was affected by month of planting (P<0.01), the plants being taller in August. The interaction month x accession was significant (P<0.05), but the accession CIAT 17434 was about 2 cm shorter than the others in both planting months (Table 10). Maximum height at the end of the establishment period was greater for August (27.4 cm) than for Sep‐ tember (18.2 cm).

the advantage of reduced tillage over zero tillage to establish vegetatively *A. pintoi* [28]. The literature shows a general agreement among researchers in that some sort of soil disturbance

Soil Management for the Establishment of the Forage Legume Arachis pintoi as a Mean to Improve Soil Fertility...

**Month CIAT accession Cover, % Plant Number Plant height, cm**

August 18744 6.2 ± 0.8 a 106 ± 6 a 13.8 ± 1.6 ab

September 18744 5.8 ± 0.7 NS 113 ± 3 ab 12.1 ± 1.0 a

**Table 10.** Mean ± standard error of cover (COV, %), plant number (PN, plants/50 m2) and plant height (PH, cm) per

It has been suggested [25] that seedlings facing more root competition from existing vegeta‐ tion responded to fertilisation, whereas those without competition had a lesser or nil re‐

In the winter season planting of experiment 1, fertilisation failed to stimulate COV of slash‐ ed plots, those supposedly with a larger competition from existing pasture. In the dry sea‐ son planting, fertilisation was detrimental to COV in the slashed plots, in contrast to [25]; finally, in the rainy season the effect of fertilisation was negligible. The second experiment showed a positive effect of fertilisation on COV only when herbicide was applied and the dried vegetation was burned. When plots were slashed, but not burned, the effect of fertili‐ sation on COV was positive. Nevertheless, when the slashed plots were burned, the fertilisa‐

Fertilisation with 23 kg P/ha, 25 kg K/ha, 20 kg S/ha and 20 kg Mg/ha had a positive effect on COV (83.4% *vs.* 61.3%) and PH (12.0 cm vs. 8.6 cm) when the soil was prepared with 4 pass‐ es of disc harrow, but with zero tillage, fertilisation reduced both COV (25.0% vs. 30.6%) and

As suggested by the inconsistent results of our trials and those of the literature, fertilisation appears not to be of great importance for the establishment of *A. pintoi*, when vegetative ma‐ terial is used. The lack of P response on *Arachis* species has been reported by other research‐ ers. In experiment 2, single superphosphate was used, and perhaps the use of this source could explain, partially, the lack of response. Also, the very low P levels on soils at CEIEGT

Means followed by the same letter are not statistically different at P≤0.01.

month of planting by accession combination in experiment 3.

tion effect on COV was negative.

PH (8.4 cm vs. 10.1 cm) [28].

NS= Non-significant.

sponse.

17434 6.4 ± 0.8 a\* 109 ± 5 a 11.9 ± 1.4 b

18748 5.1 ± 0.7 b 97 ± 6 b 14.3 ± 1.6 a

17434 5.1 ± 0.7 NS 124 ± 2 a 9.6 ± 0.9 b

18748 5.2 ± 0.6 NS 99 ± 4 b 10.0 ± 0.9 b

5.9±0.42 103.8±3.29 13.3±0.87

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61

5.4±0.38 112.0±2.61 10.6±0.55

is necessary to assure establishment [29, 30].


**Table 9.** Combined effect of vegetation control x burning x P-fertilization treatments upon *A. pintoi* CIAT 17434 mean cover (COV, %, ± standard error).

**Figure 5.** Effect of time after planting (4, 8 and 12 weeks) upon soil covering (%) of three *A*. *pintoi* accessions in ex‐ periment 3.

#### **3.4. Discussion**

In experiment 1, reduced tillage gave better results than zero tillage during the winter sea‐ son, but the opposite occurred in the dry season. As soil moisture and temperature condi‐ tions increased in the rainy season, the difference between reduced and zero tillage not disappeared and was significant. Other trials conducted in the same region have indicated the advantage of reduced tillage over zero tillage to establish vegetatively *A. pintoi* [28]. The literature shows a general agreement among researchers in that some sort of soil disturbance is necessary to assure establishment [29, 30].


Means followed by the same letter are not statistically different at P≤0.01.

NS= Non-significant.

for the August planting it took 45, 46 and 56 days for accessions CIAT 17434, CIAT 18744 and CIAT 18748, to cover 5% of the soil, respectively. Values for September were 55, 50 and 55 days. Plant height was affected by month of planting (P<0.01), the plants being taller in August. The interaction month x accession was significant (P<0.05), but the accession CIAT 17434 was about 2 cm shorter than the others in both planting months (Table 10). Maximum height at the end of the establishment period was greater for August (27.4 cm) than for Sep‐

**Table 9.** Combined effect of vegetation control x burning x P-fertilization treatments upon *A. pintoi* CIAT 17434 mean

**Figure 5.** Effect of time after planting (4, 8 and 12 weeks) upon soil covering (%) of three *A*. *pintoi* accessions in ex‐

In experiment 1, reduced tillage gave better results than zero tillage during the winter sea‐ son, but the opposite occurred in the dry season. As soil moisture and temperature condi‐ tions increased in the rainy season, the difference between reduced and zero tillage not disappeared and was significant. Other trials conducted in the same region have indicated

**Cover, %**

Without 2.39 ± 0.45 With 2.18 ± 0.54

Without 2.48 ± 0.42 With 4.21 ± 0.91

Without 1.74 ± 0.31 With 2.59 ± 0.84

Without 3.17 ± 0.69 With 2.01 ± 0.52

**Treatment combination**

Without

With

Without

With

**Vegetation control Burning P-fertilisation**

tember (18.2 cm).

60 Soil Fertility

Herbicide

Slashing

cover (COV, %, ± standard error).

P≤0.01.

periment 3.

**3.4. Discussion**

**Table 10.** Mean ± standard error of cover (COV, %), plant number (PN, plants/50 m2) and plant height (PH, cm) per month of planting by accession combination in experiment 3.

It has been suggested [25] that seedlings facing more root competition from existing vegeta‐ tion responded to fertilisation, whereas those without competition had a lesser or nil re‐ sponse.

In the winter season planting of experiment 1, fertilisation failed to stimulate COV of slash‐ ed plots, those supposedly with a larger competition from existing pasture. In the dry sea‐ son planting, fertilisation was detrimental to COV in the slashed plots, in contrast to [25]; finally, in the rainy season the effect of fertilisation was negligible. The second experiment showed a positive effect of fertilisation on COV only when herbicide was applied and the dried vegetation was burned. When plots were slashed, but not burned, the effect of fertili‐ sation on COV was positive. Nevertheless, when the slashed plots were burned, the fertilisa‐ tion effect on COV was negative.

Fertilisation with 23 kg P/ha, 25 kg K/ha, 20 kg S/ha and 20 kg Mg/ha had a positive effect on COV (83.4% *vs.* 61.3%) and PH (12.0 cm vs. 8.6 cm) when the soil was prepared with 4 pass‐ es of disc harrow, but with zero tillage, fertilisation reduced both COV (25.0% vs. 30.6%) and PH (8.4 cm vs. 10.1 cm) [28].

As suggested by the inconsistent results of our trials and those of the literature, fertilisation appears not to be of great importance for the establishment of *A. pintoi*, when vegetative ma‐ terial is used. The lack of P response on *Arachis* species has been reported by other research‐ ers. In experiment 2, single superphosphate was used, and perhaps the use of this source could explain, partially, the lack of response. Also, the very low P levels on soils at CEIEGT (0.6 to 1.2 µg g-1 soil on 0-30 cm depth), could limit N mineralization [31], resulting in a poor legume performance.

(Gramineae), and in smaller proportions *Centrosema* and *Desmodium* [37]. Among the le‐ gumes evaluated in that area, *A. pintoi* CIAT 1434 and *Pueraria phaseoloides* CIAT 9900 out‐

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63

The cost of establishing pastures in native savanna vegetation is high when following tradi‐ tional methods. Given this, it is justified to evaluate planting systems cheaper, to promote the adoption of new forages and their use to recover degraded pasture [39]. Therefore, this trial is performed to supporting evidence to assess the effect of various types of tillage and application of phosphorus on the establishment of *A*. *pintoi* CIAT 17434 and *Pueraria phaseo‐*

The research was conducted at the Centre for Teaching, Research and Extension in Tropical Animal Husbandry of the Faculty of Veterinary Medicine, of the National University of Mexico (UNAM), located in north-central region State of Veracruz, 20 ° 4 'north longitude 97 ° 3' W and a height of 105 meters above sea level. The climate is hot and humid with rain all year, type Af (m) with average daily temperature of 23.4 ° C and average annual total pre‐ cipitation of 1840 mm (1980-1989). The soil texture ranges from sandy loam to sandy clay. The area has a hard horizon with low permeability that occurs between 5 and 25 cm deep.

were the type of weeding (slashing, S; and herbicide, H) and the burning (B) application or not (with + B and without -B), to temporarily control the growth of existing vegetation (larg‐ er plots), and thus prove its effectiveness to allow the establishment of the legumes *Arachis pintoi* CIA 17434 (Ap) and *Pueraria phaseoloides* CIAT 9900 (Pp). Additionally we evaluated the application of phosphate fertilizer or not (+P addition; no-P as single superphosphate).

Treatments were applied between 28 May and 3 June 1993. The slashing (S) was a machete to the whole plot. In S + B, the burning was applied between one and five days after slash‐ ing. The application of herbicide (H) was done using a backpack sprayer, applied in bands 50 cm wide, spaced 1 m apart from the center of each. The dose was 0.96 kg (2 l) of a nonse‐ lective systemic herbicide (Glyphosate). The product was dissolved in 200 l of water and ap‐ plied 15 days before seeding. In H + B, herbicide application was the same way as above,

*Ap* vegetative material, was inoculated with the specific *Rhizobium*, by means of a suspen‐ sion prepared with nodulated roots, washed and crushed to release *Rhizobium* bacteria, then adding cold water and molasses, placing the suspension in a refrigerator, performing all procedure in the shade. Each kg of root was added 1.5 kg of molasses (as adherent) and 7.5 l

of degraded native pasture grazed by cattle. The treatments

standing for their performance and good adaptation [38].

The soils are acidic (pH 4.1 to 5.2), and are classified as Ultisols.

The factorial combination between legumes and fertilizer was the subplot.

burning 15 days after application, only the bands where the herbicide is applied.

*loides* CIAT 9900 in native pastures.

*4.1.1. Characteristics of the experimental site*

**4.1. Materials and methods**

We used an area of 6.000 m2

of cold water.

In experiment 2, burning was directed to reduce competition from existing grasses, since the way *A. pintoi* vegetative material was planted assured a close contact with the soil. However, burning, as well as fertilisation, did not show a clear positive trend either on COV or on PHT.

When only herbicide was applied in bands in experiment 2, pasture canopy height was not reduced, leading to reduced PH of *A. pintoi*. On the other hand, when the herbicide treated vegetation was burned, PH of *A. pintoi* was not impeded. Non-burned plots gave slightly taller *A. pintoi* plants than those burned. *A. pintoi* CIAT 18744 flowers less and produces a denser stolon mat than the other two accessions and it also has a vigorous initial growth, covering the soil more rapidly than the CIAT 17434 accession [32-33]. For this reason, a bet‐ ter behaviour during establishment, particularly with respect to COV and PN was expected from this cultivar. Nevertheless, in experiment 3, COV performance at the end of establish‐ ment was similar to that of CIAT 17434 (8.5% *vs.* 8.7%) and only slightly better than CIAT 18748 (7.5%). Then, the 3 accessions behaved similarly during establishment. Rates of plant emergence are considered to be good, as *A. pintoi* is a legume that can have a strong dor‐ mancy [34]. However, emergence (from 125 seeds originally planted/plot) of new branched plants/plot was not so bad, considering that these values ranged from 70% to 90% for three accessions. Therefore, there was low coverage but high number of new branched plants. This situation is common for *A. pintoi*, which is characterized by its slow establishment, as has been reported [6, 35-36]. Zero tillage failed to stimulate a rapid establishment of *A. pintoi* in these trials, the reproductive mechanisms of this species ensure that eventually it will es‐ tablish and encroach within the pasture. Our experience with this legume is that eventually it ends up to be the dominant species when associated with native pasture, Stargrass, or to both. A good strategy would be to establish *A. pintoi* in strips with reduced tillage at high density. This will result in a rapid establishment of a mixed sward in a minimum of time.

#### **3.5. Conclusions**

Neither fertilisation nor burning were successful in enhancing *A. pintoi* establishment; slashing did not improve establishment either. On the contrary, herbicides were effective and improved establishment over slashing. The best alternative to introduce *A. pintoi* into a native pasture is by reduced soil tillage in strips using, within the strips, 8 kg of pure live seed pods/ha; or 0.70 m between rows and 0.35 m between planting positions for veg‐ etative material.
