Number of plants/m2 from
Pasture (rangelands) degradation in the humid tropics of Latin America is a fact that dates back several decades, and to date not only has not been resolved, but tends to worsen according to the unfavorable economic situation of livestock in the region .
In Mexico, according to a report , 75% of the degradation is caused by deforestation (25.8%), overgrazing (24.6%) and changing land use (agricultural and urban-industrial, 25.5%). The report adds that, in the north as well as in the southern of Mexico, livestock have overgrazed pastures and supports excesives stocking rates, causing a radical change in the floristic composition of rangelands and reduced permeability of the soil, increasing runoff and causes accelerated erosion thereof.
In this paper we addressed several land management practices for the establishment of the forage legume
In the most recent experience, three land preparation management experiments were conducted, in order to evaluate the establishment of
Previously, in 2006, two experiments were carried out in order to assess the establishment of
Also, were evaluated two treaments to establish
In other experiment, two methods of soil preparation were evaluated in a native pasture. The two methods, conventional tillage and minimum tillage were evaluated under the establishment of
2. Establishment of
Arachis pintoiKrapov & W.C. Greg. as a cover crop in citrus plantations of Veracruz, México
The citrus crop in Mexico is one of the most important agricultural activities, both in area established as the value of marketing. At the end of 1999, 322.000 ha of orange (
2.1. Materials and methods
In April 1996 we established two experiments on commercial farms located in the municipalities of Martinez de la Torre and Misantla, Veracruz, Mexico (20 º 03 'north latitude and 97 ° 03'longitud west), with hot and humid climate (24 º C average and 1980 mm annual rainfall), and no definite dry season, at 112-151 meters above sea level. Figure 1 presents the data of temperature and rainfall recorded during the course of the experiments, which is typical of the region, whereas data of 20 years, except for rain April, where the normal is half of that shown in graph mentioned.
2.2. First experiment
This was done in a lemon orchard Persian 3-year-old plantation trees with 7 x 7 m. We evaluated the establishment as cover crop of the ecotypes: CIAT 17434, 18744 and 18748. The field was prepared with cross harrowing, 20 cm deep. AP 17434 was used for vegetative material (stolons 20 cm in length) while the remaining were planted with seeds (two seeds per planting point). All ecotypes were inoculated with
In the case of coverage, the trend of the data indicated the existence of an asymptotic response, so exponential models were fitted to a maximum, logistic and sigmoid, using the routine "Regression Wizard" program SigmaPlot . The model that final showed the best fit to the data coverage with rational values, was the three-parameter sigmoid, which is described below:
where “Y” is the coverage in percentage, at a “X” time, given in weeks; “a” is the maximum coverage value predicted by the model; “e” is the base of natural logarithms; “X0” is the time to “Y” reaches 50% of the value of “a”; and “b” is a constant of proportionality indicating the slope of the "S" on the right side (the higher the value, the greater slope), ie how fast it reaches the value of “a”.
2.3. Second experiment
In this case, the orchard was located in the municipality of Misantla, Veracruz, and consisted of an orange plantation with coffee plants from 14 and 8 years old, respectively. The arrangement of citrus planting was 6 x 6 m, with four coffee plants around each orange tree. A week before the start of the experiment, the native vegetation was controlled with mechanical slashing and application of glyphosate (2 L/ha). The establishment of
A randomized blocks design was used, in an split-split plot arrangement, being fertilization treatment the main plot and subplot planting method, sub-divided into two planting densities. This resulted in 12 treatments with four replicates each. The total area was 2268 m2, and the experimental unit was 144 m2.
We measured the percentage of coverage, number of plants/m2 and plant height (cm, five plants per replication), at 4, 8, 12, 16 and 20 weeks post planting. Coverage data, number of plants and plant height were subjected to analysis of variance, and means were compared using the Tukey test from the SAS statistical package . The soil was analyzed at the beginning of the experiment and 16 months later to determine changes in organic matter, soil acidity, as well as levels of nitrogen, phosphorus and potassium. Economic estimates were made to determine costs of establishment, maintenance and return on investment, compared to traditional management of weed control in citrus plantations. Were considered: the cost of slashing of the land, legume plant material and its planting labor, fertilization (P, K, Mg), land preparation, with disking, hoeing; and herbicide application.
2.4.1. First experiment
|17434||2.5 ± 0.24*||3.1 ± 0.28||3.2 ± 0.33||0.0875|
|18744||3.8 ± 0.76||3.8 ± 0.51||4.2 ± 0.48||0.5833|
|18748||8.3 ± 0.33||7.7 ± 1.45||8 ± 1.0||0.8153|
In round numbers, weeks to reach 50% and 100% coverage were 16 and 32; 12 and 24; and 13 and 26, for ecotypes 17434, 18744 and 18748, respectively;
Showing the accesion 17434 the slowest establishment, considering that at 24 weeks, plants covered an average of 84%, compared to 18744 (94%) and 18748 (91%); these latter two, very close to the corresponding value of “a” (Table 2, Figure 2 ).
2.4.2. Second experiment
Coverage. Table 4 shows the percentages of coverage, achieved five months after establishment. In all treatments the highest values were achieved with the higher plant densities and fertilization treatment, except for planting treatments with hoeing. Treatments involving the disking had values far above the other ones, regardless of the plant density and/or fertilization applied. Analyses of variance performed within each site preparation, indicated statistically significant differences (P ≤ 0.05) considering the variables plant density and fe application or not of fertilizer.
Changes in the soil. In relation to changes in soil properties, increases were recorded for the content of nitrogen, phosphorus and potassium, although there was a decrease in organic matter content (Table 5).
Economic considerations. Economic estimates indicated that establishment costs per hectare (in U.S. dollars) for the year in which the experiment was performed, varied according to the evaluated treatments, being lower for those without fertilization (US $ 294, 410 and 396) in compared with those receiving fertilizer (US $ 356, 472 and 473) for treatments with disking, weeding and hoeing, respectively. Moreover, the expenses incurred to control weeds in one hectare included the purchase of a commercial herbicide (glyphosate), an adherent and implementation of both. It imported US $ 222.
2.5.1. First experiment
The number of plants for the three ecotypes at 12 weeks, was on average lower compared with those found by  in one of three experiments with
Moreover, it appears that the ecotypes evaluated here shown in the early stages of establishment a tendency of erect growth. It has been indicated  a range from 14.4 to 21.0 cm at 12 weeks post planting date, regardless of the treatments.
With respect to coverage, the R2 values showed good predictive power for the environmental conditions during the study. No one model predicted a maximum coverage of 100%, because the measurement time was only 24 weeks.
In Colombia  evaluated in citrus plantations the same ecotypes, and found 8 months after that Ap 17434 was much lower coverage (32%) compared with the other ones (73% on average). On native pastures , found in another experiment with Ap 17434 that its establishment was even slower, since the accession planted with no-tillage or reduced tillage, with or without fertilization (P, K, Mg, Ca, Zn, Cu and B), needed 20 to 21 weeks to achieve 50% coverage.
The lower rate of coverage by the accession 17434 was also confirmed , on the experiment developed in this same region comparing four species of forage legumes (
|Organic matter (%)||2.2||2.0||- 0.20|
|Nitrogen (Kg/ha)||8.9||28||+ 19.1|
|Phosphorus (Kg/ha)||6.0||40||+ 34|
|Potasium (Kg/ha)||86||301||+ 215|
Moreover, the ecotypes established by seed showed a higher rate of coverage, however, however, these differences in the velocity of establishing tend to disappear as time passes.
2.5.2. Second experiment
The coverage obtained with the disking treatment with plants every 35 cm along the furrow, and with or without fertilization are considered acceptable and are superior to those reported for
Respect to changes detected in the soil properties, the increase in the concentration of N could be attributed to a transfer to the soil of the element present in the leaves of
By comparing these costs with the traditional management of weed control in citrus orchards, we found that the costs for these plantations were around US $ 222 per year. Economic estimates in coffee plantations in Nicaragua , mentioned that the relative costs (%) in the establishment and maintenance of the associations were higher in the first two years, compared with the traditional control of weeds, but at that time the use of herbicides was lower between 30-50%. Establishment costs in the three experiments [see 10] fell in the range of US $ 282 to 623 (the exchange rate in 2001) in terms of inputs applied. Although costs for the establishment of
3. Establishment of
Arachis pintoiin native pastures of Mexico
Research results from the hot humid areas of México and from other parts of Latin America showed that the forage legume
3.1. Materials and methods
3.1.1. Site characteristics
Three experiments were conducted during 1991 and 1996 at the Centre for Teaching, Research and Extension in Tropical Animal Husbandry (CEIEGT, its acronym in Spanish) of the Faculty of Veterinary Medicine, of the National University of Mexico (UNAM). The Centre (CEIEGT) is located in the eastern coastal plain of México about 40 km West of the Gulf of México coast line at 20° 02’ N and 97° 06’ W, at 112 m a. s. l.
The climate is hot and humid, with rains all year round. Mean yearly rainfall was 1,917±356 mm from 1980 to 1997. Monthly rainfall is highly variable being September (322 mm) and October (248 mm) the rainiest months while March (85 mm) is the driest. The coldest and hottest months are January (18.9 °C) and June (27.8 °C). Minimum daily temperatures from November to February (winter) are around the critical range of 8-10 °C, below which the growth of C4 tropical grasses is severely reduced [21-23]. These combinations of rainfall and temperature lead to a seasonal DM production pattern, a common situation in the tropics of Latin America: A high growth rate on the rainy season followed by poor growth during the winter and dry seasons.
The experiments were conducted in different years. Temperatures were typical of each season, but the current maxima were below, and the current minima above the long term (1980-1997) mean (Figure 3a). Total rainfall during experiment 1, December 1991 to September 1992, was 39% above average (Figure 3b). Rainfall in the experimental planting seasons was 339 mm in winter (November 29, 1991 to February 14, 1992), 637 mm in the dry season (March 2 to May 18 of 1992) and 1,352 mm in the rainy season (July 2 to September 17 of 1992). Rainfall was 19% above average during experiment 2 in 1993, but rains in 1996 were 43% below average for experiment 3 (Figure 3b).
The soils are acid Ultisols (Durustults), with a range in pH from 4.1 to 5.2, and an impermeable hardpan between 0 and 25 cm in depth, that result in a inadequate drainage during the rainy and winter seasons. The soil texture is clay-loam with low levels of P (< 3 ppm), S (< 30 ppm), Ca (< 3 meq/100 g) y K (< 0.2 meq/100 g). Both cation exchange capacity and aluminum saturation increase with depth, but the latter do not reach toxic levels for pasture plants .
3.1.2. Experiment 1. Reduced and zero tillage, with or without fertilisation
The study was conducted to test the combined effects of tillage type: reduced and zero, and fertilisation with (kg/ha): P 22; S 25; K 18, Mg 20; Ca 100; Zn 3; Cu 2 and B 1, or no fertilisation, in a four treatment combination: T1, reduced tillage and fertilisation; T2, reduced tillage without fertilisation; T3, zero tillage and fertilisation; and T4, zero tillage without fertilisation. Reduced tillage consisted of four passes of a disk harrow, while zero tillage only required the elimination of pasture vegetation by machete to ground level.
The experimental area was 2,000 m2 (50 m x 40 m split in two plots of 1,000 m2 - 25 m x 40 m). These plots were divided in two sub plots of 500 m2 (25 m x 20 m), of which one sub plot was fertilised. Three 2,000 m2-experimental areas were used: one per each climatic season (winter, dry and rainy season).
3.1.3. Experiment 2. Type of control of native pasture growth, with or without P fertiliser
This experiment tested the combined effect of the type of pasture vegetation control: herbicide (glyphosate) or slashing (by machete) with or without burning of dead vegetation, and with or without localised P-fertilisation which resulted in eight treatment combinations. The choice of treatments attempted to reduce competition to
Slashing was done by machete and burning was carried out between 1-5 days after slashing. A 2% aqueous solution of glyphosate (480 g of isopropyl amine salt of glyphosate/l) was applied on a 0.25 m wide strip 15 days before planting; burning was done 15 days after herbicide application.
The planting legume was done between June 28 and July 3. Application of herbicide and herbicide plus burning, and slashing or slashing plus burning, were applied 15-16 days and 3-5 days earlier, respectively. Vegetative material, 0.25 m length stolons with eight nodes, was used for planting. This material was inoculated just prior to planting with a specific
3.1.4. Experiment 3. Establisment of Arachis pintoi accessions using seed pods
This experiment compared the establishment of three
3.2. Measurements and statistical analyses
The response variables were: 1) plant number (PN, plants/m2) by counting; 2) plant height (PH, cm), on each plant within the sampling quadrat, measured with a ruler from the soil surface to the uppermost part of the plant; and 3) soil covered by the legume or cover (COV, % of quadrat area covered by the legume) measured with the aid of a 1 m2 quadrat, divided into 25 squares, which was placed over the row. These measurements were done on weeks 4, 8 and 12 after planting . In experiment 1, PH was not measured, but COV was measured again at 24 weeks after planting.
In experiment 1, there were no field replications, since it was perceived that treatments applied in larger areas would have a closer resemblance to that of farmers’ fields. Also, if several sampling quadrats were used within each treatment plot, this would yield information as useful as that obtained from randomised complete block designs. In experiments 2 and 3, the design was a randomised complete block design with 3 blocks as replicates. The treatment arrangement was a split-plot in experiment 2, where the main plot was the combination of type of pasture vegetation control (slashing and herbicide), while the combinations of burning (with and without) and P application (with and without) were the sub-plots; additionally the effect of time after planting was considered a sub-sub-plot. The treatment arrangement of the third experiment was a split plot, in which the main factor was the combination of month of planting by accession and time after planting the sub-plot. Here, number of plants was expressed as “plants/50 m2”, in order to be clearer and avoid fractions of plant/m2. Analyses of variance were done with linear additive models in accordance to the experimental design . The natural log transformation of the response variable was used if its response to time was exponential. If necessary, linear or exponential relationships provided rates of increase with time in the measured variables. Also, means comparisons using Tukey's test were done when was necessary.
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 seasons. 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).
|T1:||Reduced||With||1.36b ± 0.06||0.78a ± 0.06||2.56 a ± 0.17|
|T2||Reduced||Without||1.70a ± 0.09||0.73ab ± 0.07||2.56 a ± 0.22|
|T3||Zero||With||0.81c ± 0.03||0.60b ± 0.02||0.96 b ± 0.09|
|T4||Zero||Without||0.82c ± 0.04||0.59b ± 0.03||0.80 b ± 0.07|
|Effect of week after planting:||1.16** ± 0.04||0.68NS ± 0.02||1.72** ± 0.10|
|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|
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 uniform 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).
|Herbicide||Without||14.54 ± 1.14||0.01|
|Herbicide||With||21.01 ± 1.57|
|Slashing||Without||20.89 ± 1.23||0.05|
|Slashing||With||17.09 ± 1.25|
3.3.3. Experiment 3. Establishment of three
A. pintoiaccessions 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, respectively; 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 accessions (Figure 5). Using the regression equations of cover
|Herbicide||Without||Without||2.39 ± 0.45|
|With||2.18 ± 0.54|
|With||Without||2.48 ± 0.42|
|With||4.21 ± 0.91|
|Slashing||Without||Without||1.74 ± 0.31|
|With||2.59 ± 0.84|
|With||Without||3.17 ± 0.69|
|With||2.01 ± 0.52|
In experiment 1, reduced tillage gave better results than zero tillage during the winter season, but the opposite occurred in the dry season. As soil moisture and temperature conditions 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
|17434||6.4 ± 0.8 a*||109 ± 5 a||11.9 ± 1.4 b|
|August||18744||6.2 ± 0.8 a||106 ± 6 a||13.8 ± 1.6 ab|
|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|
|September||18744||5.8 ± 0.7 NS||113 ± 3 ab||12.1 ± 1.0 a|
|18748||5.2 ± 0.6 NS||99 ± 4 b||10.0 ± 0.9 b|
It has been suggested  that seedlings facing more root competition from existing vegetation responded to fertilisation, whereas those without competition had a lesser or nil response.
In the winter season planting of experiment 1, fertilisation failed to stimulate COV of slashed plots, those supposedly with a larger competition from existing pasture. In the dry season planting, fertilisation was detrimental to COV in the slashed plots, in contrast to ; 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 fertilisation on COV was positive. Nevertheless, when the slashed plots were burned, the fertilisation 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%
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
In experiment 2, burning was directed to reduce competition from existing grasses, since the way
When only herbicide was applied in bands in experiment 2, pasture canopy height was not reduced, leading to reduced PH of
Neither fertilisation nor burning were successful in enhancing
4. Establishment of
Arachis pintoiCIAT 17434 and Pueraria phaseoloidesCIAT 9900 using minimum tillage in Veracruz, Mexico
In the watershed Gulf of Mexico region, there is a highly seasonal pasture production due to climate variability. The main genera are components of
The cost of establishing pastures in native savanna vegetation is high when following traditional 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 . 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
4.1. Materials and methods
4.1.1. Characteristics of the experimental site
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 precipitation 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. The soils are acidic (pH 4.1 to 5.2), and are classified as Ultisols.
We used an area of 6.000 m2 of degraded native pasture grazed by cattle. The treatments 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 (larger plots), and thus prove its effectiveness to allow the establishment of the legumes
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 slashing. 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 nonselective systemic herbicide (Glyphosate). The product was dissolved in 200 l of water and applied 15 days before seeding. In H + B, herbicide application was the same way as above, burning 15 days after application, only the bands where the herbicide is applied.
Legumes were planted between 3 and 5 days after applying treatments S or S + B, and between 15 and 16 days after applying treatments H or H + B.
For planting of kudzu (
Planting density was 2 kg/ha of pure and viable seed. After scarified, the seed was inoculated and seeded similarly as
We used two sampling sites per plot at random. Firstly, two rows of each plot were chosen, and then the sampling site within each row. The recommended  variables were, number of plants, plant height (cm) and coverage (%) at 4, 8 and 12 weeks post seeding. A randomized complete block design was used, with three replications and a split-plot arrangement, with the factorial combination between weeding and burning as main plots, and the combination of the two legumes with or without fertilization as subplots. We considered the costs for materials and labor costs per treatment.
4.2. Results and discussion
Climate. – The climatic parameters of precipitation and temperature were recorded from May to September 1993. The monthly average temperature was similar for the periods, ranging from 25.5 to 27.0 °C. The lowest rainfall occurred in July and highest in September with 109 and 360 mm respectively. Rainfall totaled 1257 mm. This caused flooding which affected the establishment of each legume.
Number of plants. - Analysis of variance indicated that there was a highly significant effect (P <0.01) of the species, with 1.77 and 0.55 for
The small number of
Plant height. - Analysis of variance showed highly significant differences (P <0.01) between the species:
The interaction slashing X burning was highly significant (P <0.01). The application of H+B resulted in greater plant height with 16.0 cm, followed by S-B with 15.6 cm, being H-B method the lowest height with 11.1 cm. In the case of H+B, the plant height was attributed to no competition between the legume and native grasses; also, burning causes release of soil nutrients that legumes can absorb quickly, making their establishment more effectively.
Burning, releases mineral nutrients immobilized in plant tissues, and others are transformed into simple soluble salts, readily available to the plant . In the treatment of S-B, the largest plant height was mainly due to competition for sunlight by the grass. Competition for sunlight between
Sampling at 4, 8 and 12 weeks showed highly significant differences (P <0.01) with 7.10, 12.23 and 22.39 cm, respectively (Figure 7). This increase in plant height in time was an expected effect.
The interactions species x weeding x fertilization, and weeding x species x sampling were significant (P <0.05), while weeding x fertilization x species x sampling were highly significant (P <0.01). Most probably is that the latter would have been highly significant because it contained the first two.
These results coincide with those of an experiment in Cuba , who evaluated different methods of control vegetation during the establishment of
Coverage. - The analysis of variance showed highly significant differences (P <0.01) between species:
The interaction slashing x fertilization x burning was also significant (P <0.05), resulting in the best combination of the H+B+P with 2.5% coverage, followed by S-B-P with 1.9%. Burning + fertilization promoted a good establishment of legumes. The combinations in which was planted after herbicide application, showed no significant differences for the variable coverage.
The burning x slashing x sampling interaction was also significant (P 0 <0.05). In the third sampling, treatment H+B+P was the best combination of coverage averaging 4.2%, followed by H-B-P with 2.4%. The other combinations were not significantly different from each other. The combination S+B+P coverage reached 3.7%, which is the highest value, which shows that the burning had positive influence on legume development, although interacted differently with the type of weeding and fertilizing.
The elimination of competition below and above ground, by applying H+B+P promotes the successful establishment of legumes. The lack of competition, plus the application of P, allowed to establish successfully the legume Siratro (
The higher cost of treatment to establish
The banded herbicide application without application of fertilizer is the best method for introducing vegetatively Ap in native grass pastures in north-central region of Veracruz State, Mexico.
|+ B||- P||175.85|
|Herbicide||- B||- P||142.15|
|+ B||- P||143.21|
5. Establishment of
Arachis pintoiCIAT 17434 by two tillage methods in a native pasture of Veracruz, Mexico
In the humid tropics of Mexico, native pastures are affected by climatic variations from one season to another that make it difficult, to obtain stable yields of forage during the year.
Also, financial constraints of most producers in the tropics must be considered when trying to introduce forage species ; so it is justified, evaluate and implement systems-on planting native vegetation, different from the traditional, in order to encourage the adoption of new and improved grass species, the lower potential economic costs.
In order to improve the botanical composition of native pasture in north-central region of Veracruz, Mexico, was evaluated two methods of establishment to incorporate the forage legume
5.1. Materials and methods
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 the municipality of Tlapacoyan, Veracruz, Mexico, 20 ° 03 'north latitude and 97 ° 03' west longitude, 151 m. The climate is hot and humid on the type Af (m) (e), with an average temperature of 23.4 ° C and an average annual rainfall of 1980 mm. Soil characteristics are presented in the Table 12.
|Ca (meq/100 g)||5.1||5.0||4.2||4.0|
|CEC (meq/100 g)||7.1||6.8||5.7||5.5|
|Al saturation (%)||2.8||1.5||1.7||1.8|
The study was conducted during the three seasons representative of this region: winter or "North" from November to February; drought: March to June, rain or summer: July to October. Weather conditions for the experimental period by time are presented in Figure 9.
Experimental design and treatments. We used a completely randomized design with factorial arrangement of 2 x 2: Conventional or minimum tillage, and fertilization or not, within each period and 12 observations (no repetitions) per treatment (T), resulting in:
T1 = Conventional tillage plus fertilizer
T2 = Conventional tillage without fertilizer
T3 = Minimum tillage plus fertilizer
T4 = Minimum tillage without fertilizer
T1 and T3 were: P (22), S (25), K (18), Mg (20), Ca (100), Zn (3), Cu (2) and B (1) kg / ha. Each period included a an experimental area, with dimensions of 50 m x 40 m (2000 m2), divided into two parts along: one, conventional tillage; and another with minimum tillage. Then each part was subdivided again in width to the treatments with and without fertilization. Each treatment involved 12 observations (no repeats) within the corresponding area of 9 m2 each for thorough preparation, and 18 m2 for minimum tillage.
Land preparation. In T1 and T2, were allocated strips of 3 m x 20 m, alternating with native grass, where the vegetation was slashed with desvaradora, followed by 4 to 5 passes of harrow and plowed with a hoe. On the strips, the distance between rows and plants within them was 80 and 50 cm, respectively. The legume is seeded with a seed depth of 15 cm.
Minimum tillage. For T3 and T4, there was a land clearing with machete, were traced rows of 20 m long, spaced every two meters, and the rows were holes (seed points) every 50 cm, diameter and depth of 20 and 15 cm, respectively.
Planting dates were in Nov 29/1991, March 2/1992 and jul 15/1992, with plant material, placing 3-4 stems of 15 cm long, with only three or four leaves in the air. After 30 days, treatments were applied "with" and "without fertilization. These works were carried out in each season and in the corresponding area. Weed control was made with a hoe, in the first three months, for each treatment and time.
Variables. Data were collected at 4, 8, and 12 weeks post-seeding for number of plants, and 4, 8, 12 and 24 weeks for coverage. The useful area was 9 m2 (T1 and T2) and 18 m2 (T3 and T4). The first variable was the number of facilities within the useful area and in the second, the proportion was estimated visually apparent that the legume covered the area. The data were analyzed separately for each planting season, using ANOVA, and Tukey's test was used to compare means . Regression coefficients were estimated to number of plants (linear) and coverage (exponential) to observe trends.
5.2.1. Winter season
Number of plants. At this time, the average/treatment at 4, 8 and 12 weeks was 12.2, 15.3, 14.5 and 14.7 plants/9 m2. A significant effect (P≤0.01) by fertilizer and ages was observed; by the contrary, the interaction week x treatment was not significant. The overall average was 14.1 plants/9 m2 with a coefficient of variation of 20.0%. Treatments 2, 3 and 4 had better performance at 12 weeks.
Regarding the rate of appearance of plants, expressed this as the time in weeks to bring a new plant, was similar among treatments 2, 3 and 4 in winter and rainy seasons, while T1 needed more time to build a new plant (Table 13).
Coverage. At 12 weeks, the best coverage was in T2 (P≤0.01) with 28%, while while T1 and T3 were similar, with 22.9% and 19.0% respectively. On the contrary, coverage at T4 was 18%. The overall average for this variable during the winter season was 22.1% with a coefficient of variation of 38%.
There were statistical differences between treatments (P≤0.05), exceeding 28% of T2 with coverage, while T1 and T3 were similar, with 22.9% and 19.0% respectively. The average for T4 was 18.2%. The overall average for this variable during the winter season was 22.1% with a coefficient of variation of 38%.
Figure 10A shows the increase in coverage during the establishment period, for each treatment at 4, 8, 12 and 24 weeks. There is a considerable increase for all treatments from week 12. The maximum coverage at 24 weeks is presented in conventional tillage treatments.
The rate of coverage of the ground, expressed as the average time in weeks for the plants to cover 10% of area, is presented in Table 14.
5.2.2. Dry season
Number of plants. The averages for this variable were: 21.15, 19.75, 32.5 and 31.9 plants/9m2 assessment considering each week. T1 and T2 were statistically equal, but different from T3 and T4 (P≤0.05).
In conventional tillage, were less plants than at minimum tillage treatments. Theere are not significance for age effect, neither its interaction with soil treatment Table 13.
The best coverage (>25%) was at at 3 and 4 treatments (P≤0.05). Figure 10B shows the soil coverage at each evaluation frequency. An outsatndinh behaviour was observed for T1 after 8 weeks, achievinig 80% coverage to 24 weeks.
The age effect and its interaction with treatments were statistically significant. The shortest time to cover 10% of soil was during dry and rainy seasons at T4 (Table 14).
5.2.4. Rainy season
Number of plants. At this time, the largest number of plants/9 m2 occurred at treatments 1 and 2 (23.0 plants), compared to T3 and T4 (17.3 and 14.3 plants, respectively). Was observed an increase of plants at 8 weeks, mainly in conventional tillage treatments. The shortest time or highest rate of occurrence of plants in T1 and T4 was 1.0 weeks in time for the emergence of a new plant.
During the rainy season, soil coverage was similar among treatments (Figure 10C). The overall average was 34.5% with a coefficient of variation of 26.1%. For the rate of ground coverage, the lowest average time was observed in T4 with 2.0 weeks to cover 10% of the area (Table 14).
5.2.6. Number of plants in each season
The average of plants/m2 was largest during the rainy season (19.4 plants) followed by winter season (14.2 plants), and dry season (8,7 plants). The analysis of variance and regression coefficients for number of plants/season are shown in Table 15.
|T x W (lineal)||3||11.58||0.2532||1.37||0.9161||68.80||0.3772|
5.2.7. Soil coverage and age of plants
The best percentages of soil coverage by
|T x W (lineal)||3||1300.38||0.0001||2932.31||0.0001||958.32||0.0001|
|Coefficients||Winter season||Dry season||Rainy season|
Although the two ways to establish
Should be noted that the availability of plant material is an advantage in the evaluation of the species, as well as attempts to disseminate the same among low-income producers, because of the ease of material handling.
The null effect of fertilization on the establishment of
A study in this same experimental field , reports that when
During the experiment, the climate in CEIEGT, was very variable. This is because the region is in a climatic transition zone between the regions: coastal (subhumid) on the east, and Sierra Madre Oriental (wet), to the west, which creates a very unstable microclimate between and within years. Evidence of this was the precipitation that was 40% above the annual average and in the dry season, rainfall was 60% higher than that in the last 10 years. So, this season should be considered "atypical" and therefore the results may not be reliable. Unlike precipitation, the temperature is somewhat variable.
Based on the information presented, we conclude that: (1) establishing methods involving a conventional land preparation proved to be the best, both for number of plants to cover. (2) Although were not evaluated seasons, the best results were achieved in the r.ainy season (3) No effect was observed for either fertilization treatments. (4) whereas in the dry season rainfall was well above average, the results obtained at this time, must be taken with caution. (5) is suggested to evaluate Arachis pintoi in locations with different climate and soil, in addition to testing planting seasons. (6) must also consider the possibility of evaluating new methods of establishment, both plant material, as with sexual seed.