DRY LAND WHEAT PRODUCTION ON NARROW RAISED BEDS; A PROMISING OPTION

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1 DRY LAND WHEAT PRODUCTION ON NARROW RAISED BEDS; A PROMISING OPTION Agustin Limon-Ortega and Kenneth D. Sayre ** SUMMARY Dry land wheat and maize in the high valley of Mexico is produced using conventional planting systems involving considerable tillage. However, other new practices should be devised to increase effective use of limited rainfall. One such practice consists of planting wheat and maize on top of raised-beds that are cm apart furrow to furrow and, with two-three rows per bed for wheat and one row per bed for maize. In this document we report results of three experiments conducted using this planting system. Experiment one, initiated in 1999 crop cycle and conducted under dry land conditions compared treatments with differential crop residue management with both tied-ridges and open furrows for the wheatmaize crop rotation. Experiment two, has been conducted for three years and compared the performance of a set of bread wheat genotypes planted in permanent beds versus planting with conventional tilled raised-beds but with occasional supplemental furrow irrigation. Experiment three, initiated in 2002 under dry land conditions in two locations estimated the effect of the timing in the establishment of tied-ridges on wheat planted in conventional tilled raised-beds. Combined analysis over years for the first experiment showed that the effects that explained most of the grain yield variation were year main effect for both crops followed by residue management for wheat and then for the year-by-residue management and yearby-ridges interaction for maize. On average, either retaining all residue or partial residue removal showed a tendency to produce greater wheat and maize grain yields than when all residues were removed. Results from experiment two showed a highly significant genotypeby-tillage interaction indicating that within the two tillage options studied for the bed planting system, wheat genotypes respond differently. Results from experiment three indicated in one location (Texcoco, state of Mexico) that the timing treatments with tied-ridges produced similar wheat grain yields. However, the average yields for these treatments were greater compared to the open furrow treatment. INIFAP-CEVAMEX, AP10, km 17.5 Carr. Mexico-Lecheria, CP 56230, Chapingo, Mexico; alimon@cimmyt.exch.cgiar.org ** Corresponding author. CIMMYT Wheat Agronomist, CIMMYT, Apartado # 370, PO Box 60326, Houston, Tx; k.sayre@cgiar.org

2 INTRODUCTION Most wheat from rainfed areas in Mexico is produced in the states of Mexico and Tlaxcala. However, growers in those production areas are facing a number of constraints. One is the scarcity of rains due to El niño that in some occasions has resulted in devastating crop loses and another is soil erosion. For example, in the state of Tlaxcala, all the hill country is eroded down to tepetate, which is the final state of soil destruction (Werner, 1986). Therefore, if the farming area currently cultivated is to be preserved other management practices for wheat and maize production should be devised to ameliorate these constraints. From this viewpoint, planting wheat and maize on top of raised beds is an innovative option that can help to improve rainwater use efficiency and reduce soil erosion especially if bed planting can be combined with reduced till, permanent beds. Some previous research work has been reported from rainfed experiments with wheat drilled on raised beds ranging from 1.2 to 2.0 m apart (Abebe et al., 1994, Gerik and Morrison, 1985, Mascagni and Sabbe, 1990, and Morrison and Gerik, 1983). These reports consistently show that wheat rows beside the furrow produced more heads per square meter and grains per spike than wheat rows in the center of the bed, in the furrow, or for wheat rows planted on the flat. Consequently, the grain yield average of wheat rows planted on beds has been reported as lower than grain yield from wheat planted on the flat. However, the grain yield measured individually from rows beside the furrow has been greater than yield from rows on the flat. Accordingly, our work has clearly shown that reducing the bed widths to cm apart, the bed planting for wheat can be applied in rainfed conditions with two rows drilled cm apart on top of beds. This planting system on beds applied to wheat has many advantages over the planting system on the flat. For example, this permits the mechanical construction of dams at regular intervals across furrows between crops to hold rainfall, prevent runoff, and to provide more time for water to infiltrate. These structures are referred as tied-ridges. Reports on the study of those structures indicate that greater grain yield and water use efficiency can be obtained in crops like sorghum (Jones and Clark, 1987) and corn (Harris and Krishna, 1989, and McFarland et al., 1991). Optionally, raised beds built after the conventional soil preparation, can be left permanently intact with no further tillage operation, except for periodic reformation to maintain the shape of the bed and furrow. This option of direct seeding, that we call permanent beds, permits the implementation of crop residue strategies to maintain soil cover which may be combined with tied-ridges for greater rainwater capture and conservation (Daniel, 1950). This sort of bed

3 planting system, either permanent beds or conventional tilled-beds, represents many advantages over the conventional planting system on the flat. One is that soil compaction in the seeded area is reduced since machinery and animal traffic is restricted to the furrows between beds. The system also provides opportunity for mechanical weed control, permits band application of fertilizers, reduces crop lodging, leads to improvements in soil characters, especially for the untilled surfaced of the bed, and provides drainage system where waterlogging occurs (Sayre, 1998). The objective of this document is to summarize our work from three experiments conducted on narrow raised-beds. The first is to compare the effect of crop residue management and tied-ridges on yield of wheat and maize in rotation in permanent beds. The second, to compare the performance of wheat lines from CIMMYT breeding program planted in permanent beds with conventional tilled-beds, and the third, to study the effect of the timing of installation of tied-ridges on wheat planted in conventional tilled-beds.

4 MATERIALS AND METHODS We report three field experiments. The first two were conducted at the CIMMYT (Centro Internacional para el Mejoramiento del maiz y Trigo) station headquarters located at el Batan near Texcoco in the state of Mexico. The third one was conducted at two INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias) stations located in the states of Tlaxcala (Apizaco) and Mexico (Texcoco). Except for the first experiment that included both wheat and maize, these experiments focus on the study of wheat planted on the top of raised beds with two seed rows cm apart. Experiment one. This is a long-term experiment initiated in the summer of 1999 under rainfed conditions and permanent beds formed after a series of conventional tillage operations in the winter of Since then, the only tillage operation used has been the passage of a bed reshaper in the furrows between the beds after harvesting to reshape the beds with or without retained crop residues. This bed reshaper, in addition to the planter for permanent beds, has been adapted by CIMMYT wheat agronomy program. The bed reshaper consists of a couple of tool bars, the front one has a residue-cutting disk coulters with pressure springs followed by a narrow sweep shovel in the rear bar. Both coulter and shovel operate in the furrows between beds (Figure 1). No soil disturbance occurs on the surface of the bed. The planter has been adapted to drill two rows of wheat and one of maize on top of beds, and is equipped with spike openers for each row (Figure 2). However, other prototypes have been successfully used depending upon amount of residues and soil moisture. The trial has been managed as a RCB design in a factorial arrangement with three factors and two reps. First factor consists of three differential crop residue management, with tiedridges and open furrows as second factor, and the wheat-maize rotation as the third factor. Treatments levels for crop residue management were (1) all crop residues chopped and left as stubble, (2) all crop residues removed by baling for fodder and (3) crop residues partly removed, which was attained by removal of wheat residues cut by combine, and maize residue to just below the ear. In both cases, the remaining stalks were further chopped and distributed. Wheat and maize were planted within the optimum time for the region. Bed width was 0.75 m apart. Plots were eight beds wide (6 m) and 20 m long (120 m 2 ). Wheat plots were planted at a seeding rate of 100 kg seed/ha and maize at plants/ha. Wheat and maize genotypes planted to this trial were provided by CIMMYT breeding programs. Wheat line WEEBILL #1 (36Y) was planted in 1999 and 2000, BABAX/LR42//BABAX in 2001, and IRENA/BABAX//PASTOR in Maize line BA CMT was planted in 1999

5 and 2000, CMS in 2001, and BA CMS in Plots were fertilized using NH 4 NO 3 as N source at a rate of 120 kg N/ha. Grain yield and yield components (not reported here) were collected from the two center beds. Experiment two. This trial was initiated in the summer cycle 2000 and established as a RCB design with a split plot arrangement and three reps. Main plot was the comparison of permanent beds with conventional tilled-beds. The concept of permanent beds and their management is as described for experiment one. Conventional tilled-beds have been formed each year after following the conventional procedures, disking and chisel plow, for soil preparation. Subplot consisted on a set of advanced lines from the bread wheat and rust resistance programs at CIMMYT. This trial was occasionally watered with light furrow irrigations when severe drought stress periods appeared to damage the crop. Experiment three. This trial was managed as RCB design with split plot arrangement and three reps under conditions of conventional tilled-beds as described for experiment two. Main plot consisted on the study of tied-ridges installation timing. Treatment levels for the main plot included open furrows and tied-ridges build about days before planting, at the time of planting, and at the end of tillering. Two bread wheat varieties (Nahuatl and Tlaxcala) developed and recently released by INIFAP were planted as split plot treatment at a seeding rate of 100 kg seed/ha in four beds (80 cm apart) by 15 m long (48 m 2 ) plots. Plots were fertilized using urea as N source at a rate of 70 kg N/ha split-applied at planting and tillering. Plots were harvested by hand, grain yield and yield components (not reported here) were collected from the center two beds and two meters long.

6 RESULTS AND DISCUSSION Experiment one. According to the analysis of variance across years, the effects that explained most of the variation for grain yield of wheat and maize were the year main effect followed by residue management for wheat and then the year-by-residue and year-by-tied ridges interaction for maize (Table 1). Wheat grain yield ranged from 3974 kg/ha in 2001 to 6266 kg/ha in 2000, while for maize it ranged from 4904 kg/ha in 1999 to 7903 kg/ha in Those wide ranges within each crop can be mostly attributed to weather conditions that varied over years (Table 2). For example, weather conditions during the 2001 crop cycle were characterized by a scarce but uniform rainfall distribution, while 2002 was characterized by a very dry onset for the rainy season followed by fairly well distributed rainfall from July to September. Crop residue treatments showed that wheat grain yield is increased as the amount of crop residues on soil surface left as stubble is increased. The average grain yield of the treatment with all crop residues chopped and left as stubble was 5081kg grain/ha, while the treatment with all crop residues removed for fodder by baling was 4366kg grain/ha. This contrasting result has an important implication; the lower grain yield produced by the latter treatment means that tied-ridges on bare soils can not replace crop residues as stubble as a mean to store an equivalent amount of soil moisture and then produce similar grain yield. Our hypothesis is that soil water accumulated by the tied-ridges is easily lost by evaporation from bare soil in addition to the poor soil physical/structural stability, that results from the absence of residues as soil protection which does not permit rapid water infiltration. However, the function of tied-ridges as a means to reduce water runoff should always be considered. The initial maize data for the 1999 crop cycle is not included to discuss the year-by-residue interaction since we assume that the first relevant results were provided from 2000, the second year of the trial. The effect of crop residue management over years on grain yield of maize is shown in Figure 3a. Treatments with crop residues, either all left as stubble or partly removed, showed a remarkable effect on maize yield. This effect was more noticeable in 2001, when the amount of rainfall was only 385mm (Table 2), since the maize yield from leaving all crop residues treatment was 7214 kg/ha, while grain yield from removing all residues treatment was 6110 kg/ha. Accordingly, in the 2002-growing season when the amount of rainfall was 481mm, the partial residue removal treatment showed an outstanding performance compared to the all crop residues removed treatment (Figure 3a). This result is an indication that maize crop in a permanent bed system, requires a certain minimum level of soil cover with crop residues, which depends upon the amount of rainfall in each environment.

7 The effect of tied ridges on maize yield is apparently more related to rainfall intensity rather than to annual quantity. For example, in the 2000 and 2002 growing seasons, the treatments with tied-ridges produced greater maize yield than treatments with open furrows (Figure 3b). Those two seasons were characterized by a moderate drought periods followed by a rainstorm of 43 mm/24 hours in August 2000 and 38 mm/24 hours in July 2002 (Table 2). In contrast, the 2001 growing season, the maize yield in treatments with open furrows was greater than in treatments with tied-ridges. Even though the 2001 growing season was drier (as can be seen by lower yields) than the other years, this grain yield difference can presumably be attributed to an excess of soil water in treatments with tied-ridges produced by the frequent light rains (data not shown) that characterized this year. In either case, no appreciable water runoff was observed after rainstorms in treatments with crop residues as stubble and tied-ridges. Experiment two. Data was analyzed separately for each breeding group and growing season. Results showed large genotypic differences, but more importantly, the tillage-bygenotype interaction was highly significant in most years-breeding programs (data not shown). This suggests that the wheat crop response to tillage systems, within the bed planting options studied, tends to be associated with the genotype. On the other hand, the genotypes that on average showed the greatest grain yield, also had a tendency to produce consistently heavier kernel weight (>40 mg/kernel) with less lodging levels in permanent beds compared to conventional tilled-beds. Some examples of those genotypes are PASTOR//MUNIA/ALTAR in 2000 and 2001, and MUNIA/ALTAR84//AMSEL in 2002 from the bread wheat program, and TRAP#1/YACO//BAV92 in 2000, BABAX/LR42//BABAX in 2001 and PBW65/2*PASTOR from the rust resistance program. Those results indicate clearly that any program intended to transfer this planting technology to wheat growers, should first identify the varieties are best adapted to not only the bed planting system itself but also the tillage system to be used. Experiment three. The two bread wheat varieties studied in this experiment, Tlaxcala and Nahuatl, did not show grain yield differences in the two test locations. Average grain yield for Apizaco was 2881 kg/ha while for Texcoco 1409 kg/ha. This difference might be attributed to the amount of rainfall during the growing season that was 619 mm for Apizaco and 267 mm for Texcoco (Table 3). Tied-ridges treatments in the location of Texcoco produced greater grain yield than open furrow treatments (Table 4). However, grain yield within tied-ridge installation timing treatments were similar, which can be attributed to the most significant rainstorm that occurred in July when all tied-ridged treatments were already established.

8 Despite the fact that scarcity of rains dominated the location of Texcoco during the growing season, it is interesting to note that soil moisture measured to 60 cm depth decreased as tiedridges building was delayed over the growing season, from before planting to tillering (Table 4). The location of Apizaco did not show grain yield differences (Table 4). Soil in this area is very sandy with low water holding capacity, which may explain the negligible effect of tied-ridges on wheat grain yield and soil moisture. Therefore, to really get advantage of the rainfall amount in areas like this, other practices like permanent beds with soil surface crop residue retention should be studied. Results from this experiment have at least two implications. One is that tied-ridges have a beneficial effect on grain yield of wheat planted on conventional tilled-beds, but this effect depends on the rainfall intensity and the time in the growing season that the rainfall occurs. The other is that even tied-ridges may not always have an effect on grain yield, but the bed planting system with beds along the contour of the slopes, is an option to reduce water runoff and perhaps erosion from heavy, intense rainstorms.

9 CONCLUSIONS The first experiment demonstrates how important proper crop residue management is for a permanent bed situation in order to enhance grain yields of wheat and maize grown in rotation. On average, grain yields in both crops increased as the soil cover from crop residues increased. The effect of tied-ridges was more critical to grain yield formation of maize than on wheat, and depended upon rainfall (mostly rainstorm intensity) conditions. According to results from experiment two, the implementation of the bed planting system to a farm level, requires first the identification of the adequate wheat variety. In this sense, INIFAP has been doing research work to identify the wheat varieties, commercially available, that are adequate for the conventional till-bed planting system. Results have shown that varieties Tlaxcala and Nahuatl can be planted. The use of tied-ridges with either conventional tillage or permanent beds seems to be an excellent approach that combines the overall benefits of bed planting with enhanced moisture conservation. However, this potential benefit depends upon rainfall intensity, and the time it occurs. Tied-ridges should be installed before planting to maximize the possibilities of obtaining the benefits. Even though the bed planting system offers possibilities to reduce the effects of drought stress on wheat and maize, and to decrease soil erosion, the spread and adoption of this system, either permanent beds or conventional tilled-beds, is limited by various factors. These include availability of equipment (lack of appropriate small-scale planters and choppers), the common practice by farmers to remove crop residues for animal fodder, grazing of residues, and the need develop these new systems with active farmer participation in their fields.

10 REFERENCES Abebe, M., T. Mamo, M. Duffera, and S. Y. Kidanu Crop response to improve drainage of vertisols in the Ethiopian hihglands. J. Agr. and Crop Sci. 172: Daniel, H. A Water conservation for wheat production in Oklahoma. Soil Sci. Proc. 15: Gerik, T. J., and J. E. Morrison, Jr Wheat performance using no-tillage with controlled wheel traffic on a clay soil. Agr. J. 77: Harris, B. L., and J. H. Krishna Furrow diking to conserve moisture. J. Soil and water Cons. 44: Jones, O. R., and R. N. Clark Effects of furrow dikes on water conservation and dry land crop yields. Soil Sci. Soc. Am. J. 51: Mascagni, H. J., and W. E. Sabbe Nitrogen fertilization of wheat grown on raised, wide beds. Arkansas Agric. Exp. Sta. Rep. Series p. Mcfarland, M. L., F. M. Hons, and V. A. Saladino Effects of furrow diking and tillage on corn grain yield and nitrogen accumulation. Agr. J. 83: Morrison, J. E. Jr, and T. J. Gerik Wide beds with conservation tillage. J. Soil and water Cons. 38: Sayre, K. D Ensuring the use of sustainable crop management strategies by small wheat farmers in the 21 st century. Wheat Special Report No 48. Mexico, D. F.:Mexico. Werner, G Los suelos en el estado de Tlaxcala. Altiplano Central Mexicano. Universidad Autonoma de Tlaxcala. 132 p.

11 Table 1. Mean squares from analysis of variance of wheat and maize as affected by years, residue management and tied-ridges at CIMMYT (El Batán, Texcoco Estado de Mexico) station, Source of variation df Wheat Maize Year Error a Residues Ridges Residues*Ridges Error b Year*Residues Year*Ridges Error c ** ** ns ns ** * CV, % Mean, kg/ha ns, not significant. *, significant at P 0.05 and ** significant at P 0.01 ** ns ns ns ** * Table 2. Rainfall (mm) and maximum rainfall intensity (mm/24hours, number in parenthesis) data during the summer growing cycles at CIMMYT (El Batan, Texcoco Estado de Mexico) station for 1999, 2000, 2001, and Month * Monthly rainfall May June July August September October 4 (NA) 104 (41) 74 (11) 203 (58) 101 (25) 97 (34) 45 (12) 109 (19) 80 (14) 152 (43) 64 (11) 12 (4) 54 (27) 69 (13) 97 (22) 54 (26) 91 (29) 20 (18) 36 (16) 50 (14) 132 (38) 91 (19) 79 (14) 36 (18) Total rainfall, mm * Planting date for maize is May and for wheat is June.

12 Table 3. Rainfall (mm) and maximum rainfall intensity (mm/24hours, number in parenthesis) data during the summer growing cycles at two locations in the states of Tlaxcala and Mexico in Month * Location Texcoco, Edo Mexico Apizaco, Tlax June July August September October 42 (15) 103 (26) 8 (3) 52 (8) 62 (21) 128 (36) 153 (22) 65 (19) 213 (32) 60 (12) Total rainfall, mm * Planting date for wheat is June. Table 4. Effect of tied-ridges on wheat grain yield (kg/ha) and soil moisture (mm H 2 O/60 cm depth) in two locations in Location Tied-ridges Texcoco, Edo. Mexico Apizaco, Tlax installation timing Grain Soil Grain Soil yield moisture yield moisture Open furrow Before planting At planting End of tillering NA Average NA = Data not available. Treatment not harvested in two reps because of variable soil conditions.

13 Figure 1. Bed reshaper to maintain the shape of the bed and furrow of permanent beds with or without retained crop residues.

14 Figure 2. Prototype of planter for wheat in a permanent bed system. XI IRCSA CONFERENCE -- PROCEEDINGS

15 Figure 3a and b. Maize grain yield as affected by crop residue management, tied ridges, and year of harvest at CIMMYT station, Texcoco, Mexico Fig. 3a 7500 All residues removed 6500 Residues partly removed All residues left as stubble Year of harvest 8500 Fig. 3b With tied-ridges Without tied-ridges Year of harvest