Study área

The study was conducted in the municipality of Tequila located in the state of Jalisco, Mexico. It has an altitude between 500 and 2 900 m and the main climates are: warm subhumid and semiwarm, the temperature oscillates between 14 and 26 °C, with a precipitation of 700-1 100 mm annually and Leptosol and Luvisol as dominant soils. The municipality is the third place in area at state level, with a total of 4 720 hectares of agave in the 2015 year.

Research techniques

A survey was applied to the agaveros in the municipality of Tequila who practice two agrosystems: a) traditional agrosystem with polyculture; and b) conventional agrosystem with monoculture. The characteristics of land plots were: a) plantations of Agave tequilana Weber var. azul; b) plants older than one year; c) plantations with polyculture; and d) plantations with monoculture. The population of agave producers in the municipality of Tequila was 101, from which a sample size was calculated with a reliability of 95% and an accuracy of 10%, resulting in 49.21≈ 50 producers. The sample was distributed in 25 farmers who practiced ATP and 25 ACM.

Data were analyzed with the statistical package for social science (SPSS). Parametric (Student-T- test for dependent data) and non-parametric (U Mann-Whitney for two independent samples, contingency tables and correlation coefficient) statistical tests were performed to measure and compare agroecological practices performed in two management forms: conventional agrosystem with monoculture (ACM) and traditional agrosystem with polyculture (ATP).

Agroecological indicators and practices

Indicators of agroecological practices were used according to ^{Reijintjes et al. (1992)}, who propose five ecological principles for the design and management of sustainable agroecosystems: 1) to ensure soil conditions mainly contribution of organic matter; 2) to optimize and balance availability and flow of nutrients, especially nitrogen fixation, and the complementary use of external fertilizers; 3) to minimize losses through practices with soil and water conservation; 4) to optimize pest and disease control; and 5) synergy of use of genetic resources, combining in integrated agricultural systems with a high degree of functional diversity.

^{Moreno (2010)} proposes something more specific which is an agronomic management index (IMA) consisting of five indicators: 1) number of practices that allow the diversification of species; 2) amount of organic matter in soils; 3) number of practices that provide optimal soil conditions; 4) type of management of pest and disease control; and 5) type of weed control. They assume that the greater the IMA value the ecosystem tends to be more sustainable, since agroecological practices that are used are environmentally friendly, are more economically accessible, and are socially inclusive because agricultural practices involve more to the producer with the agroecosystem.

Based on the previous methodological proposals, this research considered eight agroecological practices: 1) intercropping (polyculture); 2) incorporation of organic matter into the soil by livestock grazing; 3) agave plantation in level curves; 4) soil and water conservation works; 5) crop rotation; 6) land rest; 7) Age staggering of agave plants; and 8) decreased application of herbicides. An index of agroecological practices in Agave tequilana (IPAAT) was generated based on the number of practices used by producers to their agave plantations. The IPAAT values were as follows: null= 0 practices, low= 1-2 practices, medium= 3-4 practices, high= 5 practices, very high= 6-7 practices and excellent= 8 practices. The survey also was included the perception of producers about reasons and benefits of agroecological practices in agave plantations.

Agroecological practices in ATP and ACM

The agroecological practices analyzed in this research for ATP and ACM are: 1) intercropping (polyculture); 2) incorporation of organic matter into the soil by grazing livestock; 3) agave plantation in level curves; 4) soil and water conservation works; 5) crop rotation; 6) land rest; 7) Age staggering of agave plants; and 8) decreased herbicide application.

Intercropping (polyculture)

This practice is exclusive to ATP, 44% intercrop agave with maize and beans, 24% intercrop only with maize, 8% cultivate a mix of beans and peanuts, another 8% cultivate maize, beans and peanuts, while 4% only intercrop agave and peanuts, an equal percentage with fruit trees such as lime, avocado and plum, and finally, 8% intercalate maize, peanuts and fruit trees (Figure 1a and 1b). ^{ASERCA (2000)} states that most farmers believe that introducing crops such as maize in their plantations leads to competition for nutrients and, in a contrary opinion, some producers pointed out that fertilization and sanitary measures applied in maize, peanut or beans are useful and allows them to obtain additional income.

Figure 1 a) intercropping of agave with maize; y b) intercropping agave with bean. 

Producers differ about the purpose of intercropping, however it is important to note that even ACM producers have a positive opinion and even prefer intercropping, but the pressure of the tequila industries force them to maintain monoculture. The main reason for intercropping maize is to obtain food for cattle and human consumption (28%), another percentage only cultivates products for human food (20%) and 16% food exclusive for livestock. In all cases, agave producers argue that only the first years of cultivation are intercropped (three to four), after that agricultural practices are difficult to do. According to ^{Valenzuela (2000)}, suggests intercalated crops area relevant when they are short-cycle, legumes and are harvested on time.

Incorporation of organic matter into the soil by grazing livestock

The producers point out the pertinence of the pastoral use in their plots because this practice has three purposes: weed reduction through cattle feeding; b) biological fertilization of plantations; and c) reduction of pasture purchases.

In the ACM, 40% (10 agave producers) introduce livestock on their plots, out of which 32% do so in rotation from one plantation to another and 8% do it in a seasonal or deferred way before the dry season. On the other hand, 60% of ATP producers graze livestock (48% rotational and 12% continuous).

The months for cattle grazing are after the rainy season and especially when other crops were intercropped into the agave plantations. Free grazing is carried out from the third year of the agave life cycle, since the plant is more vigorous and therefore less vulnerable to damage by livestock. They introduce from 3 to 18 animal units per ha, the average is 7.64 heads. They feed from one to seven years of the total biological cycle, averaging 3.66 in ATP and 4.2 years in ACM. The months free of cattle during the productive cycle in plantations oscillates from 1 to 34 months, the average is 4.14 months. In ACM, the mean is 6.4 months and is 2.6 months in ATP.

introduce three to 18 heads or animal units per ha, the average is 7.64 heads. They feed from one to seven years of the total biological cycle, averaging 3.66 in the ATP and 4.2 years in the ACM. The months they leave the cattle free during the productive cycle in the plantation oscillates between one and 34 months, the average is of 4.14 months. In the ACM the mean is 6.4 months whereas in the ATP it is 2.6 months.

Producer have conflicting opinions about this practice, on one hand, some say that livestock grazing is necessary to remove soil, fertilize the soil, weed control and avoid pests, it coincide with what ^{Moreno et al. (2011)}; ^{Hernández (2014)} say. On the other hand, there are producers who do not graze their livestock because they consider it harmful to crops and soils. Half of them (50%) do not do this practice because it slows agave growth and decreases its quality, compacts the soil, damages the plants and when seedlings are newly planted they are pulled by cattle, in agreement with the indicated by ^{García and López (2009)}. Some agave producers point out that the use of cattle is aggressive to plantations, because they bite mother plants or in some cases when they are small (from one to three years) cattle tear them from root and the same is done with the seedlings, causing damage and therefore losses. For these reasons they recommend the use of remuda (horses, mules and males), since they have observed to be less harmful to agave plants.

Agave plantation in level curves

Plantations in level curves is a practice carried out by the great distillers and has been spreading among small producers. Although it is suggested planting rows in curves at a level to reduce soil losses at tolerable levels, this agroecological practice is used a little bit, only 24% of the producers apply this method in equal proportion between ACM and ATP; that is, 12% for each system. In ACM, it is performed when the slope is from light to flat and in the ATP when the slope is from moderate to flat. The level curves are related to the works for soil and water conservation; however, the agave producers perform in a higher percentage, conservation works and not level curves in their plots.

In lands where this practice is not used, it is due to traditional schemes of cultivation, used to planting in rows. On the other hand, they indicated that when there is land in “ceboruco” (land of eroded hills) it is recommended. In this research in Tequila it was found that only 12 out of 40 agave producers make level curves in comparison to conservation works. ^{Rodríguez et al. (2005)} indicate that the improved native maize crop system intercalated with mezcalero agave under level curves and living walls system is feasible for areas that do not have water for irrigation in degraded hills.

Soil and water conservation Works

Studies conducted by ^{Guevara et al. (2012)} in agave conclude that the lack of knowledge of crop management (cultural and agronomic) and of the optimum regions for agave, it has triggered soil degradation process. Some strategies proposed to reduce erosion are: 1) soil conservation practices on land with slopes of 5% or higher, such as: a) minimizing agricultural implements use to the minimum; b) not to use agrichemicals; and c) manual cleaning and weed control in crops; and 2) to avoid the partial or total elimination of natural vegetation.

The percentage of producers performing these conservation practices is high (80%). These include: work of soil and water conservation (34%) (Stone constructions, roadways, little dam, chains, sacks with stones or soil and wall with loose stones); gather the “trash” (litter and branches) and place it by the shore; construction of ditches, earthen bunds, fences and masonry. It should be noted that, conservation works (58.82%) are more frequently constructed in ATP compared to ACM. The t student test (t= 2.359, p= 0.022) indicated that there is a statistical difference between both ways of management.

Crop rotation

Crop rotations increase yields, add organic matter to soil and thus increase soil fertility. It is recommended a rotation of different species and nutritional needs, as is the case of beans and maize, these crops are the most rotated by agave producers (44%). More rotations are done in ATP (30%) than in ACM (14%). The reasons for rotations are: 34% of agaveros indicated that it is to rest their land, to avoid nutrient wasting, to soften and to “vitamin” soils and 8% of them do it to change seeds because it improves the production and nourishes the soil. Nitrogen addition is achieved by rotating legume crops, it suppress insects, pests and diseases by effectively breaking the life cycle of pests, and the absence of these eliminates the fundamental mechanisms of self-regulation (^{Altieri, 2009}).

Soil rest

This type of practice improves soil conditions in plantations by improving fertility and microbiota (^{Sivila and Angulo, 2006}). When a land is cultivated without rest, the soil has no time to recover part of its natural fertility necessary for the plants growth. 78% of agave producers do this type of practice, they are distributed on 36% in ACM and 42% in ATP. Most of the producers indicated that this practice is fundamental in soils recovery. The rest period varies between one and two years with an average of 1.48.

Age staggering of agave plants

Age staggering is a strategy against the possibility of total loss or production reduction and maintenance of agave plantations. In the municipality of Tequila, agave producers have plantations of different ages to have continuous production every year, although the most common is that they have plantations with differences of two years. The vegetative cycle of agave plant lasts an average of 7 years, allowing this practice. For this reason, 48% of producers carry out age staggering in their plantations, from which 30% are producers of ATP and the rest of ACM.

Agave producers have an average of 5.2 years using age diversification in their plantations, although they had two cases of producers that have been doing age staggering of agave plants for 20 years. This activity is a practice of recent incorporation into agrosystems. Regarding the average number of years that agave producer have practiced age staggering is 4.2 years in ATP and reached 6.7 years in ACM.

The producers reduce the cost of production with this method through two ways: 1) selection of agave shoots, the producers separate the healthy agave shoots of their own plantations and grow it according to size, age and vigor; and 2) gradual investment, as the agave producers have the economic resources they acquire the young shoots, for this reason heterogeneous plantations are observed in a land plot.

Decreased application of herbicides

Producerscarryoutthefollowingpracticesthatsignificantly reduce the use of herbicides: 1) agroecological: manual control of weeds, free grazing of livestock and production of organic inputs; and 2) agroindustrial: precise or minimum dosages of herbicides to reduce costs (based on supplier recommendations) and collective purchase. More than half of the producers opt for manual control to reduce the cost and dependence of herbicides, out of which 38% are from ATP and 30% from ACM. The proper use of herbicides doses was only recurrent in ACM.

Index of agroecological practices in Agave tequilana (IPAAT)

Descriptive analysis of agroecological practices was complemented by performing t Student tests for the whole set of agroecological practices. The U Mann Whitney test was performed to know similarities between different practices and it was found that in rotations and intercropping between both agroecosystems, they show significant statistical differences (Table 1).

An index of agroecological practices in Agave tequilana (IPAAT) was generated based on the number of ecological practices done by producers of ATP and the ACM, as shown in Table 2. Agave producers were concentrated between medium and very high levels because they carry out from three to seven agroecological practices per unit area (ha).

Most of the ATP producers (72%) were concentrated between high and very high levels. The average number of practices into ATP was 5.52 which is classified at the very high IPAAT level. While most of the ACM producers ATP producers. This means that even in agave monocultures some practices are done that can be considered agroecological. A t Student test (t= -0.5292; p= 0) was applied showing no statistical difference.