Characteristics of the study area

The study was carried out in Juchitán de Zaragoza, which has the largest surface area of the coastal plain of the Istmo of Tehuantepec, Oaxaca and coincides with Irrigation District No. 19. It includes, in addition to the municipal seat, five municipal agencies and two agencies of cop.

It is located between the parallels 16° 12’ and 16° 38’ north latitude and 94° 44’ and 95° 08’ west longitude, in an altitudinal range of 0 to 500 m. The climate is Aw₀ (w) ig, classified as warm subhumid, the driest of the subhumid, with rains in summer. Average temperature of 26 °C and an average annual rainfall of 978 mm. The natural vegetation extends over a large plain and includes low deciduous forests and thorn scrub. Vertisols, Phaeozem, Arenosols, Luvisols, Fluvisols, Cambisols, Solonchak and Gleysols soils predominate (^{INEGI, 2010a}; ^2010b; ^{UABJO, 2014}).

Methodological process

The research was based on participatory action research according to ^{Colmenares (2012)}. The approach was mixed, exploratory and descriptive. The design was non-experimental and the data was generated directly without prior processing. The criterion for the selection of the communities was dedication to agricultural activity, as there are fully fishing communities.

The investigation included six communities in the municipality: Juchitán de Zaragoza, Álvaro Obregón, Emiliano Zapata, La Ventosa, La Venta and Chicapa de Castro. The diagnostic methodology to analyze the communities and their context was that of the participatory rural survey (SRP) by ^{Selener et al. (1999)}). To generate the field information, the survey was used through the application of a questionnaire, the dialogue with the producers and the field trips.

The questionnaire was structured in two sections, the diagnosis to identify the social, economic, productive and organizational characteristics in the peasant production units, from its analysis the diagnosis was reached. The second was for the characterization of cropping systems, using the methodology for the study of agroecosystems of ^{Hernández-Xolocotzi (1977)}. The questionnaire was applied to farmers by stratum (localities). The selection criteria were that they were corn growers and belonged to the 1 200 registered in the CADER registry.

The sample size was 60 producers (5% of the population); 22, 20 and 18 for AE1, AE2 and AE3, respectively. The selection was made by the 'snowball' technique. It consists of a first approach with a local expert to whom the questionnaire is applied; then name potential key informants in the community.

The data generated was classified in environmental, economic, social and technological axes for analysis. 103 study variables were proposed at the beginning, to reduce dimensionality a principal components analysis (PCA) (SAS) was applied. With this analysis, the 10 variables with the greatest relative weight were selected, five from the biophysical axis, two from the social axis and three from the economic one.

In the technological axis there were no variables due to their homogeneity. The second criterion for selecting the variables was the ‘value judgment’ according to ^{Masera et al. (2000)}, to incorporate variables for the characterization of AE: social axis (2); economic (2); and technological (8). Finally, 22 variables were considered in the biophysical axes (5); social (4); economic (5); and technological (8) (Table 1).

Canonical discriminant analysis (CDA) was performed with the CANDISC (SAS) procedure to detect discrepancies between localities. The Mahalanobis square distance and multivariate tests with an approximation of F.

Identification and characterization of agroecosystems

According to the study of the determining variables, in the discriminant functions of maximum separation (p< 0.01), three agroecosystems were identified: 1) maize agroecosystem in Juchitán de Zaragoza-Chicapa de Castro; 2) maize agroecosystem in Álvaro Obregón-Emiliano Zapata; and 3) maize agroecosystem in La Venta-La Ventosa (Figure 1).

Figure 1 Separation of agroecosystems by canonical discrimination with their determining variables. 

Maize agroecosystem in Juchitán de Zaragoza-Chicapa de Castro (AE1)

AE1 is located in the towns of Juchitán de Zaragoza and Chicapa de Castro, at altitudes of up to 22 m; Average annual temperature of 27 °C and maximum and minimum of 31.7 and 16.8 °C, respectively. Average annual rainfall is 980 mm. ^{Aragón et al. (2005)} indicate that in Oaxaca, corn is grown from 0 to 2 800 masl under different climatic and edaphic conditions.

According to ^{Cervantes-Herrera et al. (2015)}, corn produces acceptably in areas where it rains annually from 600 to 1 000 mm well distributed for four to seven months. It comprises zapotecas peasants (100%) with peasant production units (UPC) made up of five individuals, the head of the family with the collaboration of two children. This is advantageous, ^{Serrano-Ojeda et al. (2016)}, report that in the center of Puebla the UPF are made up of four people (Figure 2).

Figure 2 Representation of the corn agroecosystem in Juchitán de Zaragoza-Chicapa de Castro (AE1). 

According to ^{Cervantes-Herrera et al. (2015)}, family intervention is a form of productive training, transmission of knowledge and assessment of productive activity. Only 13.6% of the farmers belong to a working group organized for the production of corn, a very low percentage that does not reflect group participation and does not ensure the operation and continuity of projects or other processes.

The farmers of AE1 grow native corn of the Zapalote Chico breed, known locally as Xhuba’huini. It is endemic to the Istmo of Tehuantepec and the coastal regions of Oaxaca and Chiapas at average altitudes of 600 m, although samples of other races are reported between 1 550 and 1 900 masl (^{Aragón et al., 2005}). The main characteristics refer to its earliness (90 days), resistance to drought and pests.

It is a low-growing plant (110-150 cm) that supports the strong winds in the area. Its cobs are short with a low number of rows of semi-floury grains, it has the lowest glume/grain index in the mexican races, large germ and average protein content of 12.7%, one of the highest of the corn races.

It is the basis of food and is used to prepare tortillas, atoles, corn and make tortilla chips (^{CONABIO, 2010}; ^{Cabrera-Toledo et al. 2016}). The preference of local genotypes occurs in several states of Mexico (^{Herrera et al., 2002}; ^{Vásquez-Carrillo et al., 2010}); For example, in Chiapas (^{Aguilar-Jiménez et al., 2011}) and Puebla (^{Zagoya, 2015}), it is due to its lower cost and desirable characteristics for food preparation.

The cultivation begins with the mechanized preparation of the land (90.9%) and traditional (9.1%) with an Egyptian plow. Sowing is under two methods: traditional with the use of animal and human force (68.2%) and with mechanical seeders (31.8%). Due to time issues, given the short cycle of Zapalote Chico maize, farmers combine conventional technology (primary tillage) and traditional technology (secondary tillage, furrowing, sowing and weeding), also reported by ^{Turijan et al. (2012)}.

81.81% fertilize only with nitrogen, 46 to 69 kg N ha^-1 in the first labor or hilling. This treatment is achieved with two and three lumps of urea. It is low when considering the 92-46-00 formula recommended by ^{Cabrera et al. (2018)}. The main pest is the arriera ant (Atta spp.) and for its control they use Dichloro Diphenyl Dichloroethanol scattered in the nests.

59.1% of farmers in AE1 manually control weeds. In San Felipe Teotlalzingo, Puebla, machinery is used to till the soil, but sowing, weeding and fertilization is manual using a shovel and hoe or with the team (^{Zagoya, 2015}). They allocate an average of five ha for planting corn, divided into two to four plots. 41% of the farmers use practices to preserve soil fertility by incorporating crop residues and manure; crop rotation, legume-associated crops, etc.; efficient in traditional agriculture (^{Cervantes-Herrera et al., 2015}).

Only 13.6% of the farmers of AE1 have participated in technical assistance programs through the organization to which they belong. ^{Macedo et al. (2003)}, indicate that the traditional farmers of the common Cofradia de Suchitlan, Colima, receive government support, but lack training and technical assistance, which denotes the lack of technical advisers that enable the continuous adaptation of these AE that face challenges to improve its sustainability.

The harvest is manual after three months; they generally hire outside wages. Thanks to the precocity of the Zapalote Chico, the plots are sown three times a year under three humidity conditions: temporary, irrigation and residual humidity. The latter is known as Igudxa sowing, which takes advantage of the residual humidity of the storm and the serene ones from October to December.

A single cultivation system under temporary and two multiple cultivation systems was identified, one under irrigation and temporary (31.8%), and the other under irrigation, temporary and humidity (13.6%), with an average accumulated production of 3 665 kg ha^-1 year^-1, low if compared with the average yields of 2 950 kg ha^-1 cycle^-1 reported by ^{Cabrera et al. (2018)}. Per crop cycle, 10 wages are hired out of the 30 required for cleaning canals, planting, hilling, irrigation and harvesting.

The UPF main source of income is agriculture, from the sale of corn and livestock (sale of milk, cheese and animals in local markets). Similar to the AE of Tierra Caliente, Michoacán (^{Villa-Méndez et al., 2008}) and the common Cofradia Suchitlán, Colima (^{Macedo et al., 2003}), where 60 and 83% of the peasants, respectively, depend economically on the UPC.

The average monthly income per UPC is $6 750.00 and exceeds that reported by ^{Serrano-Ojeda et al. (2016)} for the central region of Puebla, with an income in those with the highest food security of $2 566.00 per month. In AE1, 27% complements income with the support of the Productive PROAGRO, useful for the production process and other basic needs. The UPC in the region that are supported are lower than those of Tulancingo, Hidalgo, where 36% of the corn growers receive it, possibly because there are more consolidated organizations (^{Ayala-Garay et al., 2013}).

The destination of the production varies, 36.4% of the UPC of AE1 corn for self-consumption, 45.4% sells only surpluses and the remaining 18.2% sells everything produced due to income needs or the lack of infrastructure for storage. In Tlaxcala, 40% use corn for self-consumption, 2% for sale, and 58% for both (^{Damián et al., 2007b}; ^{Damián et al., 2008}). This differs from what was reported in the common Cofradia Suchitlan, Colima, where 83% of the UPC satisfy their food needs (^{Macedo et al., 2003}).

This indicates that corn meets different needs by being sold directly or marketed transformed due to its various forms of consumption. The commercialization is local and is sold by the liter (750 g), at a price of $7.00. Economically, the rent of labor is important in this AE, as they are day laborers outside the UPC with an income of $170.00 day^-1 and an average of 8 days ha^-1 per cycle, although it can be up to 12 days ha^-1 per maize cycle.

Maize agroecosystem in Álvaro Obregón-Emiliano Zapata (AE2)

AE2 is located at an altitude of 6 m. The maximum temperature is 29.8 °C, the annual average is 26 °C and the average precipitation is 942 mm annually. Structurally, AE2 presents a variant in the livestock subsystem with the rearing of sheep under an extensive grazing regime, in contrast to AE1 and 3 which are dedicated to raising dual-purpose cattle (breeding and milk).

The peasants are zapotecos (95%) and mestizos (5%) (Non-zapoteco speakers) and do not belong to any organization for the production of corn. UPF are made up of 6.5 people on average. The head of the family is in charge of the UPC and 2 to 3 of the children collaborate in it.

^{Serrano-Ojeda et al. (2016)} report that in the center of Puebla the UF are made up of four people and two actively collaborate in the UP. According to ^{SAGARPA (2017)}, traditional agriculture is based on the intensive use of family labor.

In the same way, they grow Zapalote Chico corn. To reduce time, the preparation of the land is mechanized (100%) and the sowing is mechanical (75%) and traditional with Egyptian plow (25%). 80% use nitrogen fertilizers (46 kg N ha^-1), at the time of hilling and matting, far from the doses of 92-46-00 (kg ha^-1 of nitrogen, phosphorus and potassium, respectively) recommended by ^{Cabrera et al. (2018)}. They do not use insecticides, since the pests are not significant.

Weed control is manual and is only carried out at the edges of the plots (90%). 50% incorporate diverse amounts of crop residues and manure from the livestock subsystem prior to soil preparation to preserve fertility (Figure 3).

Figure 3 Representation of the maize agroecosystem in Álvaro Obregon-Emiliano Zapata (AE2). 

Farmers in the Atoyac River sub-basin, Oaxaca, indicate that it is necessary to fertilize, carry out two weeding, rotate with legumes, and incorporate manure and residues to achieve harvests (^{Ruiz-Vega and Silva-Rivera, 2006}). In addition, they are an important source of organic nitrogen (^{Salazar-Sosa et al., 2009}; ^{Salazar-Sosa et al., 2010}), allow the development of microorganisms that promote fertility (^{Damián et al., 2013}), improve structure and texture, increases aeration, root penetration, retains water and strong and healthy plants resistant to pests and diseases are achieved (^{Aguilar et al., 2003}; ^{Damián et al., 2008}).

This scheme is similar to that of Tlaxcala, where 84.4% use nitrogen fertilizers and 66.4% incorporate manure into the soil (^{Damián et al., 2007a}; ^{Damián et al., 2007b}). Likewise, Mayan farmers from Peten, Guatemala, do not use fertilizers or fertilizers for the milpa and weed control is manual (^{Lara et al., 2012}). In AE2, each producer cultivates 3.6 ha in 1 or 2 plots.

According to ^{Ayala-Garay et al. (2013)}, is similar to Tulancingo, Hidalgo; where they cultivate 3.36 ha on average, but less than Tlaxcala (^{Damián et al., 2008}), where they are 5 ha and higher with respect to the central region of Puebla with 2.36 ha on average (^{Serrano-Ojeda et al., 2016}).

The cultivation area is important since, the larger the area, the higher the production, which enables self-sufficiency and surpluses for sale, provided that there are the necessary inputs (^{Pat-Fernandez et al., 2011}). In this AE, three crops are also grown per year: a simple temporary system (75% of farmers), multiple irrigation and temporary systems (75%) and an irrigation system, temporary and humidity (10%); with which a cumulative production of 3 312 kg ha^-1 year^-1 is generated.

In this there is no technical advice for growing corn. In each crop cycle, an average of five wages are hired to support sowing, hilling and harvesting activities. The UPF depend on agricultural activities, direct sale of corn and the production of tortilla chips, livestock activities (sale of animals) and the salaried work of their children outside the UPC, with an average of 12 wages per cycle for each of the members.

The income includes the support of the Productive PROAGRO (85% of the producers); for an average monthly income of $3 675.00. This diversity occurs throughout the country and is similar to that of the Tehuacán Valley, Puebla, where peasants cultivate, raise goats, trade firewood and non-timber species (^{Aguilar et al., 2003}).

Corn is for self-sufficiency (80%) and sale (20%), similar to the 96% identified in Tulancingo, Hidalgo (^{Ayala-Garay et al., 2013}). Like the AE1, the sale is local and the liter of corn sells for $7.00. payment for labor is $130.00 per day.

Maize agroecosystem in La Venta-La Ventosa (AE3)

The AE3 is located at altitudes of 39 m, with maximum temperatures of 32.8 °C and the annual average of 27.5 °C, with annual rainfall of 1 007 mm, above the optimal range. The peasants are zapotecas and mestizo (50%).

The UPF are made up of six individuals and the activities are in charge of the head of the family and two of the children occasionally participate. Different from the four in the central region of Puebla (^{Serrano-Ojeda et al., 2016}). Likewise, farmers do not belong to work groups or local organization, a situation that does not allow for economies of scale (^{Ayala-Garay et al., 2013}).

Structurally, AE3 differs from AE2 and AE1 in the agricultural subsystem, as it is sown in the latter under humid conditions, although the livestock subsystem is similar to AE1, as it has dual-purpose livestock (Figure 4).

Figure 4 Representation of the corn agroecosystem in La Venta-La Ventosa (AE3). 

The seed is from Zapalote Chico selected from the previous harvest due to adaptation characteristics to the region and for the preparation of tortillas and chips for self-consumption (^{Ayala-Garay et al., 2013}). Land preparation is mechanized (100%) and sowing is mechanical (94.4%). 83.3% use nitrogen fertilizers at a rate of 46 to 69 kg N ha^-1, based on urea. Matte is applied one day before hilling. There are no serious pests. Traditionally they incorporate crop residues and manure (77.8%). On average, 4.7 sowings have been distributed in 1.2 plots, that is, more compact surfaces than in the other AE.

This area is higher than that used in Hidalgo, where 2.5 ha of corn are cultivated on average (^{Ayala-Garay et al., 2010}). Only 27.7% of producers occasionally receive technical advice. This situation occurs in several states of the country. In Tlaxcala, 91.6% of corn producers lack technical assistance (^{Damian et al., 2007a}; ^{Damian et al., 2007b}).

This factor is of utmost importance, since it reinforces the skills and capacities of farmers and is decisive for increasing agricultural production (^{Damián et al., 2008}; ^{Ayala-Garay et al., 2013}). In AE3, three cultivation systems were detected based on humidity, irrigation (61% of producers), temporary (22%) and a multiple system under irrigation and temporary (16.6%).

In the latter it is possible to obtain an accumulated production of 3 244 kg ha^-1 year^-1. In the Valley of Tehuacán, Puebla, the peasants have irrigated and seasonal agriculture to produce more food per year (^{Aguilar et al., 2003}). In this AE, for each crop cycle they hire an average of eight wages to support the activities of cleaning channels, sowing, hilling, irrigation and harvesting.

The average monthly income of the UPF of this AE is $6 000.00, for livestock and agricultural activities. Like AE1 and AE2, 94.4% of the producers have the support of PROAGRO Productivo. Corn is for self-supply (88.9%) and for sale (11.1%). Figures similar to those of Cuetzalan, Puebla, where 18% is sold (^{Damian et al., 2013}).

The grain is sold locally by the liter for $8.00. The hired labor generates an expense of $150.00 per day. The members of this AE also work as day laborers with 12 wages cycle^-1 to supplement their income.