Growth, Physiology, and Productivity of Bouteloua gracilis and Cenchrus ciliaris Using Moisture Retainers under Different Planting Methods

Abstract

The extensive raising of livestock on grasslands is a relevant economic activity in northern Mexico. These are regions of high climatic uncertainty and have extreme weather events, which requires the exploration of technological innovation to mitigate the negative impacts on these agroecosystems. The aim of this study was to evaluate two grass species using two planting methods and two types of soil moisture retainers and to determine their response based on growth and some physiological and productive attributes. A randomized complete block design (RCBD) was used in a split–split plot arrangement with six replications. The main plots were planted with two grass species: Bouteloua gracilis and Cenchrus ciliaris; the subplots were differentiated by two grass planting methods: seeding and seedling transplanting; the sub-subplots were differentiated by the soil moisture retainers used: (1) application on the soil of 10 t ha⁻¹ of corn harvest residue (CHR) as organic cover on the soil surface, (2) application of hydrogel at 20 kg ha⁻¹ mixed in the soil rhizosphere because it must be in contact with the root and soil due to its chemical composition, and (3) control, no application of any type of input. The seedling transplant method with the application of CHR significantly increased (p < 0.05) the plant survival percentage, on average by 31.5% in both grasses, in relation to the direct method seeding and the control. C. ciliaris showed a higher photosynthetic rate and, therefore, higher forage productivity than B. gracilis. The hydrogel only showed a moisture retention effect in the soil during the first 20 days after the transplant or sowing of the grass seed; after this period, there was no longer any effect as a water retainer in the soil. The soil cover with CHR was confirmed as a good moisture retainer with greater productivity of rangeland forage in degraded soils in arid areas.

1. Introduction

Desertification is a dynamic process that advances over time and is currently a threat to the food security and subsistence of more than two billion people in the world who live in arid areas [1]. The environmental impact of climate change is enhanced by anthropocentric activities such as the excessive use of agrochemicals and the overexploitation of the aquifer in irrigated agriculture for forage production [2,3] as well as the use of saline water, which negatively affects crop yields in agroecosystems [4].

The degradation of extensive livestock rangeland areas has a negative impact on meat production, which is one of the most common economic activities in northern Mexico [5]. There is a diversity of technological practices that mitigate soil degradation in dryland areas, but the application of one or a combination of these depends on the specific conditions of each agroecosystem. The use of native and introduced grasses, in addition to rainwater harvesting and soil moisture retention practices, is proving to be effective in areas with low rainfall [6,7,8].

The generation and validation of technology that is appropriate for the specific conditions of each region is practiced to promote productivity through soil–plant–animal management programs as part of a more sustainable and resilient vision [9]. In particular, rangeland reseeding is a frequent practice in which the choice of the species is critical given the relatively high cost and low probability of success depending on the sowing practice used [10].

Bouteloua gracilis H.B.K. [Lag.] is a promising grass for the revegetation of rangelands in arid ecosystems due to its ability of adaptation to different environments [11]. This grass species dominates in many grassland areas due to its tolerance to grazing and higher root biomass production in the upper soil profile in comparison to other grass species, as well as having the additional environmental benefit of carbon sequestration [12].

Cenchrus ciliaris L. is an invasive plant in dry climates, and it was introduced in northern Mexico as a species suitable for rehabilitating degraded areas with erosion problems and as a forage producer in rangeland areas [13]. This species is widely planted due to its high adaptability to different environments and rapid spread, for which it is considered as an alternative in the recovery of degraded rangelands. Rainwater harvesting practices and soil moisture conservation could help improve grass establishment in pastures susceptible to water deficit in arid lands [14].

The rehabilitation of rangeland involves the use of different technologies such as seedling planting, grass seeding, as well as the use of grass species with more suitable properties, after evaluating their adaptability to the agroecological conditions of the region [15]. Arid zones are vulnerable areas due to their low rainfall regime, which necessitates the use of forage species tolerant to water deficits complemented with appropriate sowing or transplanting methods, the design and construction of rainwater harvesting systems, and soil moisture retention through the use of plant covers [16,17] and soil moisture retainers [7], among other management practices. The objective of this study was to evaluate the response on the physiology and productivity of Bouteloua gracilis and Cenchrus ciliaris under different planting methods and use of moisture retainers in degraded soils in northern Mexico.

The severe deterioration of North México grasslands [15,18,19] highlights the importance of recovering the productivity of these ecosystems through rehabilitation practices such as grassland overseeding [20,21], in which the choice of species is critical given the relatively high cost and the low probability of success of this practice [22,23]. Moreover, monitoring of the established grasslands is necessary to inform decision-making to revert the soil degradation and improve the conditions of these productive areas [22]. Sowing techniques [24] and the incorporation of inputs into the soil [25,26] could increase the availability of dry matter in pasture areas and decrease the forage deficit in the region. The aim of this study was to evaluate two grass species using two planting methods and two types of soil moisture retainers and their impact on the growth and some physiological and productive attributes in northern Mexico.

2. Materials and Methods

This study was carried out in Mapimí, State of Durango, Mexico. The experiment was conducted during 2016 and 2017. The area is located at 25°52′23.65″ N and 103°43′41.74″ W at an elevation of 1176 m. The region has a BWhw(e) climate, corresponding to a very arid, semi-warm climate with summer rains and extreme thermal amplitude. The mean annual precipitation is 260 mm with a maximum temperature of 44 °C and a minimum temperature of −10 °C with an annual average of 19.4 °C [27].

2.1. Experimental Design

A randomized complete block design was used in a split–split plot arrangement with six replications. The main plots were planted with two grass species: B. gracilis H.B.K. [Lag.] and C. ciliaris L. The subplots corresponded to the planting methods: sowing seed at a dose of 5 kg ha⁻¹ per grass species and the equivalent by seedling transplant. The sub-subplots were differentiated by the soil moisture retainers used: application of 10 t ha⁻¹ of CHR on the soil surface and application of 20 kg ha⁻¹ of hydrogel mixed in the soil rhizosphere, with the control being no application of any type of product to the soil. Each experimental unit was an area 5 m long by 5 m wide with 7 furrows per treatment. Six plants were randomly selected for morphometric and physiological measurements from the five central rows of each treatment.

For the grass seedling transplant treatment, before establishing the experiment in the field, grass seedlings were grown by sowing grass seed in Styrofoam trays with the use of peat moss as substrate, under controlled mesh-shade conditions. Uniform light irrigations were applied daily, avoiding dehydration of the seedlings. Germination occurred three days after sowing in both grass species. The transplantation of the grass seedlings was carried out 21 days after germination. For direct sowing treatments with grass seed in the experimental area, this activity was carried out manually and on the same date as the sowing. For seeding, a rake was used to remove the surface layer of soil, to later spread the seed over it, trying to leave the seed slightly covered by a thin layer of soil no greater than 3 cm by raking [28].

Corn harvest residues (CHRs) were applied at a dose of 10 t ha⁻¹ on the soil surface as vegetative cover before seedling transplantation and sowing of the grasses. The hydrogel was applied manually, at the same time as the seedling transplantation and sowing of the grass seed. The hydrogel was deposited at the same depth as the root ball of the seedling applying 2 g seedling transplanted⁻¹; in the case of direct seeding, the hydrogel was applied together with the grass seed, in the same proportion as for seedling transplantation.

Hydrogel is a granular copolymer that has a dry matter content of 85 to 90%, bulk density of 0.85 g mL⁻¹, specific weight of 1.10 g cm⁻³, and pH of 8.1 [29] with the ability to increase soil moisture retention and, thereby, make better use of rain or irrigation water. The experiment was established on 28 July 2016, and the evaluations were conducted during the phenological cycles of the grasses in 2016 and 2017.

Rainfall (mm) and temperature (°C) were recorded through a HeavyWeather Pro WS 2800 (La Crosse Technology, WI, USA) semi-automatic weather station installed in the area of influence of the experiment. Using a digital electronic meter with a real-time readout (Lutron Model PMS-714, Lutron Electronic Enterprise Co., Taipei, Taiwan), the soil moisture percentage readings were recorded in a 0–30 cm depth profile. The soil moisture content vs. the energy tension (Mpa) was determined using a Soil Moisture Equipment^® model 1500F1 membrane pot (St. Barbara, CA, USA). The soil moisture drawdown curve (Figure 1) followed a negative exponential function according to Equation (1):

$$T=k{Ps}^{-n}$$

(1)

where Ps is the percentage of moisture in the soil, and k and n are constants of the regression. Thus, for the 0–30 cm profile, Equation (2) was used:

$$Ps=15.729\ast T^{-0.396}$$

(2)

The above climatic and soil parameters were measured during 2016 and 2017 in the stages of growth, development, and physiological maturity of the grasses in the period from July to November of both years.

2.2. Variables

The variables measured in this study were as follows: percentage of seedling survival, plant height, photosynthesis, transpiration, stomatal conductance, efficient use of water, and production of fresh and dry matter, which were measured from 8 days after the establishment of the experiment (DAEE). The percentage of seedling survival was measured using a simple random sampling through a transect of 3 lines for each treatment, selecting the intercepted plants in each line by direct counting per plant at 28 DAEE; while, for the variables of growth and physiology, 6 grass plants were randomly selected per treatment within the useful plot on which the respective measurements were made. Plant height (cm) was determined with the use of a tape measure throughout the growth and development stage of the grass plant in 2016. The physiological variables corresponding to photosynthesis (μmol CO₂ m⁻² s⁻¹), transpiration (mol H₂O₂ m⁻² s⁻¹), and stomatal conductance (mol m⁻² s⁻¹) were measured with the LI-6400 Infrared Ray Gas Analyzer (IRGA) (LI-COR^® Inc., Lincoln, NE, USA), and the water use efficiency was calculated based on the photosynthesis/transpiration ratio. These variables were measured during 2016 and 2017 in the summer and fall seasons of each year. At the end of the productive cycle in each year of evaluation, the fresh and dry biomass production of the grasses was measured through destructive sampling, harvesting all the plants of the experimental unit (25 m²). The calculation of production per hectare was carried out with Equation (3):

$$YPHFB=\frac{\left(WFB\left)\right(10000\right)}{25}$$

(3)

where YPHFB = yield of fresh biomass ha⁻¹; WFB = weight of fresh biomass obtained in 25 m². The dry biomass per hectare was calculated in similarly. For this variable, drying was carried out in an HAFO^® recirculating air oven (model 1600, USA) at 75 °C for 36 h.

2.3. Data Analysis

The data were analyzed with RStudio version 1.0.143 software (RStudio Inc., Boston, MA, USA). Analysis of variance and Tukey’s mean multiple range test were performed to identify the treatment effect, and regression analysis was carried out to identify the relationship between the dependent and independent variables.

3. Results and Discussion

The rainy season in the two years of evaluation (2016 and 2017) occurred in the period from July to September, with lower amounts in the other months of the year. The accumulated precipitation was 346.6 and 274.4 mm in 2016 and 2017, respectively. B. gracilis is a native species with high adaptability to moderate rainfall regimes during the growing season, and C. ciliaris is a species introduced to the study region that is widely used for reseeding rangelands in areas with low rainfall regimes [16,22].

3.1. Soil Moisture Content

Corn harvest residues (CHRs) were used as a cover to reduce evaporation and maintain the soil moisture content resulting in higher soil moisture, especially in the last week of August, due to the first torrential rain recorded in each of the two years (2016 and 2017) (Figure 2). Similar results were reported by other authors [30] who recorded higher soil moisture content when applying cover to rainfed soybean (Glycine max L.) and sorghum (Sorghum bicolor (L.) Moench) in years with irregular rainfall. In addition, the incorporation of straw mulch to the first soil profile also improved soil water retention in sunflower (Helianthus annuus L.) [31]. The incorporation of mulch or others organic residues from different crops is an important cultural practice since they have a special role in the retention of soil moisture [32]. In addition, the application of mulch alone without compost during dry periods and after small amounts of rainfall is especially beneficial to revegetation in a semi-arid rangeland [33]. Furthermore, for the oligotrophic mountain grasslands, the mulching relatively increased biomass production [34].

The H treatment only increased soil moisture during the first 20 DAEE, and then practically matched the behavior of the control (Figure 2). Other authors [35,36] reported a prolonged effect of plant-available water, suggesting that the behavior of the polymer varies depending on the physicochemical characteristics of the soil and the dose of hydrogel applied [37].

The use of hydrogel as a water retainer in the soil is a good option to optimize water use and not affect other similar grass species such as Agrostis stolonifera [38]. However, a study on oil flax showed that hydrogel application together with the seed was more effective than granular applications with traditional flax sowing machine since there was insufficient water retention where the granules were placed [39].

3.2. Seedling Survival Percentage

The survival percentage showed the same behavior trend during 2016 and 2017, corresponding to a significantly better response (p < 0.05) when either of the two soil moisture retainers (CHR or H) was used, compared to the control in both grass species, with higher values in the seedling transplant method compared to grass seeding. The average survival rate for both grasses during the two years was 77.5% when transplanting was used, compared to 55.4% when seeding (

Table 1. Survival percentage of two grass species under two planting methods and different soil moisture retainers.

Soil Moisture Retainer	B. gracilis Grass		C. ciliaris Grass
	Survival (%)
	ST	SGS	ST	SGS
2016 evaluation
CHR (10 t ha−1)	87.33 a ± 1.9	57.21 a ± 2.9	89.13 a ± 2.5	59.66 a ± 3.9
H (20 kg ha−1)	85.19 a ± 2.5	56.32 a ± 2.6	86.69 a ± 2.1	58.22 a ± 3.2
Control	69.23 b ± 2.4	49.88 b ± 3.1	71.07 b ± 3.0	51.23 b ± 3.1
2017 evaluation
CHR (10 t ha−1)	78.52 a ± 1.8	53.98 a ± 2.8	83.59 a ± 2.8	60.88 a ± 2.6
H (20 kg ha−1)	76.44 a ± 1.9	50.19 a ± 2.6	82.95 a ± 3.1	58.71 a ± 2.9
Control	60.36 b ± 3.2	45.25 b ± 3.3	65.17 b ± 2.4	51.10 b ± 2.5

^{a, b} Tukey’s test (p < 0.05). Figures with the same letters in the same column and in each evaluation year are statistically equal. ST = seedling transplanting; SGS = sowing grass seed; CHR = corn harvest residue; and H = hydrogel.

). This is possibly related to the fact that seeding implies greater risks of germination due to environmental effects, particularly because, at this development stage, a higher soil moisture content is required for seed germination compared to other phenological stages of plants [40]. In contrast, high establishment percentages have been found in grass species when using the transplanting method, which is effective even in soils with limited water availability and soil fertility [41].

The use of cover as a soil moisture retainer to reduce evaporation and the application of hydrogel to retain soil moisture improved grass emergence and growth by conserving soil moisture content. The survival percentage in B. gracilis grass was 69.5% when applying 10 t ha⁻¹ of CHR and 67.3% when applying 20 kg ha⁻¹ of H, with no statistical difference between the two methods, but higher than the control (p < 0.05) (Table 1).

Lower precipitation during winter 2016–2017 and spring 2017 significantly decreased the B. gracilis (p < 0.05) survival percentage in 2017 compared to 2016. In addition, this grass species has limitations when used for reseeding rangelands, due to difficulties in adapting under water-deficit conditions [24]. In contrast, C. ciliaris establishes well with a moderate rainfall regime, equivalent to 250 mm [42]. Some authors reported that species such as buffel grass present some limitations for growing related to seed dormancy, which affect the emergence of seedlings in the field during the establishment of grasses [43]. Likewise, the temperature and light requirements for optimal germination depend on each species of grass [44].

3.3. Plant Growth and Development

No statistical differences (p < 0.05) were observed in the plant height of the grass species between seedling transplanting and direct seeding. According to the growth analysis, B. gracilis showed a slightly higher growth rate than C. ciliaris, differentiating after 56 DAEE, highlighting the CHR treatment with exponential growth rates of 1.0 (R² = 0.94) and 1.09 (R² = 0.94) in C. ciliaris and B. gracilis, respectively (Figure 3a,b). These differences in the growth and development dynamics between the grass species suggest that they are more related to their phylogenetic nature [45,46], although both were favored by a higher soil moisture content when CHR was applied. This indicates a good adaptability of both species to degraded soils under a regular rainfall regime.

These results coincide with those reported by some authors [47] who indicate that the addition of mulch or vegetable cover on a legume significantly influenced some agronomic attributes such as the plant growth, yield, and nutritional quality of the crop. It has been found that the application of mulch or straw in saline soils significantly increased plant growth and forage yield in Guinea grass [48]. Other authors [25] reported that the addition of mulch to the soil for the establishment of grasses obtained significantly higher results in areas where the straw was not applied, since there was a greater amount of grass vegetation and biomass.

In previous studies, it was shown that productivity in grasses such as C. ciliaris, Chloris gayana, and Panicum maximum can be increased by mulching the soil as this will improve soil surface conditions, moderating abrupt changes in temperatures to assist plant growth [49].

The plant growth always showed an exponential behavior, with a stabilization trend in the last sampling dates since grasses stop growing when entering the flowering and maturity phase. This confirms the adaptation of the evaluated grasses to soil moisture conditions, conforming with the results of other authors [50].

3.4. Photosynthetic Activity and Water Use Efficiency

The higher soil moisture content in the CHR treatments showed a greater photosynthetic activity (p < 0.05) in both grass species, and no statistical difference in other physiological variables in the two years of evaluation (

Table 2. Physiological variables and water use efficiency in two grass species, two planting methods and soil moisture retainers in 2016 and 2017.

Soil Moisture Retainer	B. gracilis Grass		C. ciliaris Grass
	ST	SGS	ST	SGS
	2016	2017	2016	2017
Photosynthesis (μmol CO2 cm−2 s−1)
CHR (10 t ha−1)	14.9 a ± 1.0	13.8 a ± 1.1	17.8 a ± 0.9	17.5 a ± 0.7
H (20 kg ha−1)	13.0 b ± 0.8	12.2 b ± 0.6	15.9 b ± 0.5	14.1 b ± 0.8
Control	13.1 b ± 0.6	12.0 b ± 0.5	14.6 c ± 0.6	14.3 b ± 0.5
Transpiration (mol cm−2 s−1)
CHR (10 t ha−1)	0.740 a ± 0.03	0.716 a ± 0.02	0.860 a ± 0.05	0.804 a ± 0.07
H (20 kg ha−1)	0.786 a ± 0.04	0.710 a ± 0.05	0.851 a ± 0.04	0.837 a ± 0.04
Control	0.78 a ± 0.01	0.789 a ± 0.09	0.839 a ± 0.05	0.816 a ± 0.06
Stomatal conductance (μmol H2O cm−2 s−1)
CHR (10 t ha−1)	0.34 a ± 0.05	0.36 a ± 0.09	0.038 a ± 0.06	0.037 a ± 0.03
H (20 kg ha−1)	0.31 a ± 0.07	0.29 a ± 0.01	0.041 a ± 0.04	0.040 a ± 0.05
Control	0.33 a ± 0.06	0.30 a ± 0.02	0.035 a ± 0.03	0.039 a ± 0.03
Water use efficiency
CHR (10 t ha−1)	20.1 a ± 0.3	19.3 a ± 0.5	20.7 a ± 0.4	21.8 a ± 0.6
H (20 kg ha−1)	16.5 b ± 06	17.2 b ± 0.4	18.7 b ± 0.6	16.9 b ± 0.5
Control	16.8 b ± 04	15.2 c ± 0.3	17.4 c ± 0.5	17.5 b ± 0.6

^{a, b, c} Tukey’s test (p < 0.05). Figures with the same letters within the same column of each physiological variable are statistically equal. ST = seedling transplanting; SGS = sowing grass seed; CHR = corn harvest residue; and H = hydrogel.

). The planting methods did not show any effect on these variables (p < 0.05).

B. gracilis recorded a photosynthesis that was significantly higher (p < 0.05) with CHR showing values of 14.9 and 13.8 μmol CO₂ m⁻² s⁻¹ and 17.8 and 17.5 μmol CO₂ m⁻² s⁻¹ for the seedlings transplanted (ST) during 2016 and 2017, respectively. The efficient use of water showed a similar trend since it is the ratio of CO₂ assimilated per H₂O transpired by the plant [51]. The CHR treatment recorded higher water use efficiencies in the years evaluated (p < 0.05) compared to the hydrogel applications and the control, with an average value of 19.7 for the two years for B. gracilis and 21.3 for C. ciliaris. It has been reported that, in soils with higher moisture content, photosynthesis is favored [52]; in contrast, under low soil moisture regimes, photosynthesis decreased due to the stomatal closure effect [53].

Some C. ciliaris populations had a positive effect under water saturation conditions through changes in physiological and phenological behavior [54]. Mainly, the seasonal variability of soil moisture drives differences in photosynthetic physiology in native grass species of the genus Bouteloua [55]. In addition, some populations in North America of B. gracilis showed good local adaptation through a type of plasticity–sensitivity trade-off in photosynthesis and stomatal conductance in plant populations from arid climates [56].

3.5. Biomass Production

In both evaluation years (2016 and 2017), the production of fresh (FM) and dry (DM) biomass (g plant⁻¹) and the equivalent production yield of fresh and dry forage (t ha⁻¹) were significantly higher (p < 0.05) when CHR was applied in the two grass species, with average values for the two years of 58.7 and 75.7 g plant⁻¹ in B. gracilis and C. ciliaris, respectively. The yield also recorded average values of 0.63 and 4.47 t ha⁻¹ for the two years evaluated. The fresh and dry forage yield results were significantly higher (p < 0.05), both in B. gracilis with 4.47 t ha⁻¹ and 0.63 t ha⁻¹ of FM and DM, respectively, and in C. ciliaris with 6.87 t ha⁻¹ and 1.46 t ha⁻¹ of FM and DM, respectively (

Table 3. Fresh and dry weight as biomass production per plant and fresh and dry matter weight as yield per hectare in two grass species for two planting methods and soil moisture retainers during 2016 and 2017.

Soil Moisture Retainer	B. gracilis Grass		C. ciliaris Grass
	ST	SGS	ST	SGS
	2016	2017	2016	2017
Biomass fresh weight (g plant−1)
CHR (10 t ha−1)	131.6 a ± 2.9	117.9 a ± 1.3	155.7 a ± 3.2	145.8 a ± 3.5
H (20 kg ha−1)	120.2 b ± 2.8	111.3 b ± 3.0	130.9 b ± 3.9	135.1 b ± 3.5
Control	101.6 c ± 1.6	92.2 c ± 1.2	108.2 c ± 4.5	103.4 c ± 4.7
Biomass dry weight (g plant−1)
CHR (10 t ha−1)	61.8 a ± 3.1	55.6 a ± 1.2	80.2 a ± 3.0	71.1 a ± 2.9
H (20 kg ha−1)	54.9 b ± 2.6	48.2 b ± 3.2	54.1 b ± 4.4	60.3 b ± 3.8
Control	32.5 c ± 1.4	31.6 c ± 1.0	30.8 c ± 4.2	28.6 c ± 5.0
Yield (t FM ha−1)
CHR (10 t ha−1)	3.35 a ± 0.040	2.23 a ± 0.038	8.29 a ± 0.046	5.44 a ± 0.045
H (20 kg ha−1)	2.97 b ± 0.039	1.90 b ± 0.043	7.10 b ± 0.040	4.74 b ± 0.049
Control	2.05 c ± 0.036	1.25 c ± 0.048	4.94 c ± 0.049	3.57 c ± 0.052
Yield (t DM ha−1)
CHR (10 t ha−1)	0.76 a ± 0.017	0.50 a ± 0.019	1.81 a ± 0.031	1.18 a ± 0.027
H (20 kg ha−1)	0.69 b ± 0.018	0.43 b ± 0.016	1.58 b ± 0.023	1.05 b ± 0.031
Control	0.45 c ± 0.021	0.29 c ± 0.017	1.08 b ± 0.024	0.77 c ± 0.026

^{a, b, c} Tukey’s test (p < 0.05). Figures with the same letters within the same column of each productivity variable are statistically equal. ST = seedling transplanting; SGS = sowing grass seed; CHR = corn harvest residue; H = hydrogel; FM = fresh matter; and DM = dry matter.

). An intermediate behavior between that shown in CHR and the control was obtained when applying 20 kg ha⁻¹ of hydrogel; the control obtained the lowest productivity values (Table 3). The seedling transplanting method and CHR were associated with the productivity variables in both grass species. Other authors [57,58,59,60] also associate greater advantages with introduced grasses already adapted to region, since they usually have a higher amount of dry matter than native grasses, even though native grasses are more palatable and have higher nutritional value. The C. ciliaris tends to have a higher tolerance to drought and a higher biomass production [61]. Native populations of B. gracilis in northern Mexico show a high productive potential, and they could serve for the development of new grass varieties and can be used in restoration programs [62,63,64].

Finally, based on the results, it is advisable to continue with these types of studies in grassland areas with high environmental and productive risk due to extreme events related to rainfall and temperatures, as well as anthropocentric activities, such as an animal overload, which deteriorates the soil causing water erosion.

4. Conclusions

The percentage of surviving plants increased significantly (p < 0.05) by 31.5% in both grass species using the seedling transplant method and applying 10 t ha⁻¹ of corn crop residues. The introduced grass C. ciliaris had a higher photosynthetic rate and, therefore, greater productivity of fresh and dry forage biomass than B. gracilis. Hydrogel applications were only associated with greater soil moisture retention in the first 20 days after the experiment was established, with a low effect on photosynthesis, but higher productivity than the control. The organic cover with corn harvest residues is confirmed as a good evaporation retardant, therefore yielding higher rangeland forage productivity rates in arid lands such as northern Mexico. In addition to the economic benefit from the use of plant cover on the ground, other benefits can be obtained such as mitigating water erosion of the soil, which is very common in these regions and a common problem in these grassland areas.