An experiment was conducted at the University of Arizona Maricopa Agricultural Center, Maricopa, Arizona in 1999 to compare and evaluate agronomic and economic differences between Ultra Narrow Row (UNR) and conventional cotton row spacing systems with respect to yield, fiber quality, earliness potential, plant growth and development, and production costs. Row spacing was 10 and 40 inches for the UNR and conventional systems, respectively. Two varieties were evaluated within each row spacing, Sure Grow 747 (SG 747) and Delta Pine 429RR (DP 429RR). Lygus populations were extremely high in the Maricopa, Arizona region in 1999 which resulted in poor fruit retention from early through mid-season. As a result of poor boll load through mid-season, the UNR plots were irrigated and grown later into the season than desired along with the conventional cotton in order to set and develop a later season boll load. The mean lint yield averaged across row spacing was significantly greater (P=0.05) in the UNR row spacing at 1334 lb/A than for the conventional row spacing at 1213 lb/A. SG 747 produced 1426 and 1337lb/A of lint in the UNR and conventional systems, respectively. DP 429RR produced 1242 and 1089 lb/A of lint in the UNR and conventional systems respectively. Fiber grades were all 21 or 31 in both UNR and conventional systems. Micronaire was 4.9 or less in both varieties within the UNR system. Micronaire was high at 5.3 in the conventionally produced SG 747 resulting in discount but was acceptable at 4.7 in the conventionally produced DP 429RR. Length and strength measurements met base standards in all cotton variety and row spacing combinations. Neither the conventional or the UNR cotton production systems were profitable due primarily to high chemical insect control costs and early season boll loss. However, UNR production costs were lower by $0.09 per pound than in the conventional system on a cash cost basis and $0.14 per pound lower when considering total costs including variable and ownership costs.

In two 1999 Arizona studies, a preplant incorporated (PPI) application of Prowl (2.4 pt/A) or Treflan (0.75 lb a.i./A) followed by a topical Roundup Ultra (1 qt/A) application at the 3 to 4 true leaf cotton growth stage provided good weed control. At the University of Arizona Maricopa Agricultural Center field that had low density weed populations, a postemergence topical Staple (1.8 oz/A) application also provided good weed control was more expensive. At the Buckeye, Arizona study site, a PPI application of Prowl at a reduced rate (1.2 pt/A) was as effective as the full rate (2.4 pt/A) but a preemergence application of Prowl (2.4 pt/A) was not as effective as either of the PPI Prowl rates or PPI Treflan (0.75 lb a.i./A). A postemergence topical Staple application (1.8 oz/A) following the Roundup Ultra application did not significantly improve weed control. After one field season of experimentation and observation in Arizona UNR cotton, experience suggests that in fields with low to moderate weed populations, a PPI Prowl or Treflan application followed by a postemergence topical Roundup Ultra application will provide acceptable weed control in most fields. However, the presence of nutsedge or other difficult to control weeds may require two postemergence topical Roundup Ultra application prior to the four leaf growth stage of cotton. More research is needed to further explore weed control options in Arizona UNR cotton production systems.

A preliminary investigation was made in Ultra-narrow row cotton production on the Safford Agricultural Center to see if there was any promise in that technology for cotton producers in the high deserts of Arizona. Increases in plant populations to near 100,000 plants per acre in single lines, double lines and quadruple lines per bed were the goals of the study. In-season plant mapping to evaluate differences in plant growth characteristics were done along with yield measurements to evaluate differences. Yield increases were not seen with increases in plant populations in single row plantings nor in multiple row plantings.

Seven commercial ultra narrow row (UNR) cotton fields were monitored on a weekly basis in Maricopa County, AZ in 1999. Varieties of Delta Pine and Sure Grow were planted from April 15 to June 1 and reached cut-out after accumulating 1913 to 2327 heat units after planting. Average yield for UNR cotton was 2.1 bales per acre which was 0.4 bales per acre lower than the five year average for cotton planted on conventional row spacings. Fiber quality from gin records for 801 bales had average micronaire readings of 4.54 and grades of 11 and 21 for 74% of bales. Discounts for extraneous matter (bark, grass, and cracked seed) was 5.4% and average strength (34.8) and staple lengths (27.12) were in acceptable ranges. Total cash costs ranged from $450 to $705.

A large portion of irrigated soybean in Mississippi are planted on raised beds spaced 96.52 cm apart. There is recent interest in growing soybean in narrower rows. Previous research indicates that narrower row spacing can provide advantages over wider arrangements, including increased light interception, improved weed management and greater seed yield. Soybean was planted in 96.52 cm single rows, 96.52 cm twin rows and 50 cm rows on wide beds (200 cm) at three seeding rates. Canopy closure was monitored throughout the growing season. Soybean planted in narrow rows had consistently faster canopy closure than single rows at all site years. Similarly, there was a 10% to 13% seed yield advantage for the narrow row spacing over the single row spacing at each site year. With the introduction of novel technology, such as the twin row planter, comes equipment malfunction and/or misuse that could reduce seed yield. Producer decisions in the event of a planting/planter error can be challenging. The economic loss due to a planter error may vary by soil type due to differences in plant development. The purpose of this research is to determine the agronomic effects associated with multiple potential twin row planter errors on two distinct soil types across multiple maturity groups commonly found in Mississippi. Canopy closure of each planting error was monitored throughout the growing season. Seed yield was reduced by 9 to 18% when a whole twin row was missing compared to the untreated check at all site years.

A single field study was established in 2001 at the Safford Agricultural Center to evaluate a twin-line cotton production system. This location was part of a larger, statewide program conducted in 2001. This location consisted of two separate planting dates (PD) in which two separate planting systems were used. Results from this location indicated trends in yield increases with the twin-line production system when compared to the single or conventional production system. Lint yield increases of approximately 200 lbs. lint/acre were observed on the second PD. Lower yields were observed in the twin-line planting with the first PD which was in part due to poor seed placement with the equipment used to plant the twin-line on the first PD. Results indicate the potential for increased yield with the twin-line production system with the caveat that the proper equipment be used to plant the twin-line system to ensure precise and consistent seed placement and spacing.

Three experiments were conducted in Maricopa, Marana, and Glendale, Arizona in 2001 to measure cotton growth, yield, micronaire, and production costs in single and double seed line per bed systems on 32 and 40 inch beds. Canopy development was faster and canopy closure was greater in the double seed line than in the single seed line systems and was greater in the 32 inch than in the 40 inch row systems. At Maricopa, the single line 32 inch system yield of 1571 lbs./A was significantly greater than the yields of the other seed line/row spacing systems. The yields of the single line 40 and the double line 32 inch systems were not significantly different at 1476 and 1411 lbs. of lint/A, respectively, and the yields of the double line 32 and the double line 40 inch systems also were not significantly different at 1411 and 1396 lbs. of lint/A, respectively. There were no significant lint yield differences at the Marana or Glendale location. At Marana, the lint yields were 1063 and 1066 lbs./A for the single and double seed line 40 inch row spacing systems, respectively. At Glendale, the single and double seed line 38 inch row spacing systems yielded 1474 and 1551 lbs. of lint/A, respectively. In all 2001 experiments, there was a trend for reduced micronaire in the double seed line per bed systems compared to the single seed line per bed systems. At Maricopa, the average micronaire was 5.0 and 4.7 for the single and double seed line per bed 32 inch row system, respectively, and 5.2 and 4.9 for the single and double seed line per bed 40 inch row systems, respectively. At Marana, the micronaire was 4.7 and 4.5 for the single and double seed line per bed 40 inch row systems, respectively. At Glendale, the micronaire was 5.1 and 4.6 for the single and double seed line per bed 38 inch row systems, respectively. Production costs were similar for the single and double seed line per bed systems. Additional research will be conducted in 2002 to determine the optimum plant populations and in-row plant spacings for double seed line per bed production systems.

Three experiments at the University of Arizona Maricopa and Marana Agricultural Centers in 2002 and 2003 measured effect of plant populations on the yield of cotton planted in the twin seed-line per bed configuration. In 2002 at the Maricopa Ag. Center, the plant populations were 52800, 69200, 82800 and 96200 plants per acre (PPA) for Stoneville 4892BR and 54800, 70800, 90500 and 104500 PPA for AG3601, respectively. The two lowest plant populations which were in the range of common commercial plant densities resulted in the greatest lint yields for both varieties (an average of 1708 and 1287 lb lint/A for ST4892BR and AG3601, respectively) but there was a significant linear decrease in yield with increasing plant population. In 2003, the cotton variety Delta Pine 449BR was planted and the population densities were 22000, 29000, 36000, 46000, 51000, 61000, and 64,000 PPA at the Marana Ag. Center and 24000, 34000, 41000, 56000, 63000, 71000, and 86,000 PPA at the Maricopa Ag. Center. Cotton yield did not vary significantly as a function of population density at Maricopa and averaged 1526 lb lint/A. At Marana there was a slight trend of increasing yield with increasing plant densities with the three highest plant populations averaging 1385 lb lint/A. In the experiments with ST4892BR and AG3601 at Maricopa in 2002 and with DP449BR in 2003 there was a linear decrease in fiber micronaire with increasing density but this effect of density on micronaire was not observed possibly because plant populations Marana were lower than in the other experiments.

Twin line (two seed lines 7.25 in apart per bed) and conventional single seed line per bed cotton production systems were compared at 18 sites across Arizona and the Palo Verde Valley near Blythe, Ca. in 2002 and 9 sites in 2003. Three experiments at the Chaffin site in 2002 compared twin line plant populations of 57,000 (57K), 75,000 (75K), and 90,000 (90K) plants per acre (ppa). In 2002, the twin line system produced more lint than the conventional single line system at 4 of 18 locations; the yields of the twin line and single line systems were 1273 and 1186 lb/acre, 1572 and 1461 lb/acre, 1478 and 1290 lb/acre, and 1309 and 1210 lb/acre, respectively, at the Grasty, Ramona, Rovey, and Wells sites, respectively. In 2003, none of the experiments resulted in higher twin line system lint yields. In 2002, there were no significant differences in yield or fiber micronaire in 7 of the 18 experiments. In 2003, there were no significant differences in yield in 3 of the 9 experiments. In 2002, the twin line system produced less lint than the conventional system at 5 of 18 locations; yields of the twin line and single line systems were 2019 and 2189 lb/acre, 1400 and 1489 lb/acre, 1537 and 1845 lb/acre, 1065 and 1200 lb/acre, and 1271 and 1431 lb/acre, respectively, at the Chaffin (75K), Cooley, Hull, Papago, and Wakimoto sites, respectively. In 2003, the twin line system resulted in less yield in 6 of the 9 experiments; yields of the twin line and single line systems were 1154 and 1285 lb./acre, 1906 and 2109 lb./acre, 1797 and 1938 lb./acre, 878 and 1114 lb./acre, 726 and 821 lb./acre, and 1230 and 1404 lb./acre, respectively, at the Hull, Marlatt 1, 2,, 3, Murphy Late Plant, and the University of Arizona (UA) Marana Agricultural Center sites respectively. In 2002, fiber micronaire was reduced in five experiments; the micronaire values were 4.25 and 4.73, 4.46 and 4.78, 4.60 and 4.85, 4.76 and 4.98, and 4.93 and 5.15, in the twin line and single line systems, respectively, at the Rogers, Papago, Grasty, Hull, and Perry sites, respectively. In 2003, there were no significant differences in fiber micronaire at all 9 test locations. In 2003, visual observations suggested that the spindle pickers were unable to effectively harvest bolls the lowest bolls primarily below the cross-over point of the two2 mainstems cross in the twin line system. Hand harvest comparisons of the twin and single line system resulted in yields of 1776 and 1661 lb./acre respectively, a 6% difference at the Maricopa Agricultural Center. It was concluded that tThe inability to effectively harvest the twin line cotton is the most significant system problem with this production system.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.