Conventional Row Spacing Research Articles

Narrow row maize cultivation increased grain and forage yield of hybrids in Ohio and Pennsylvania

AbstractAlthough there has been a resurgence in interest among farmers in producing narrow row hybrid maize (Zea mays L.) in the Eastern UnitedStates, agronomic recommendations for modern hybrids are limited. To address this issue, field trials were carried out from 2016 to 2018 in Ohio and Pennsylvania (10 unique site‐year combinations), aiming to answer the following questions: (i) Do modern hybrids differ in their response to narrow (38 cm) and conventional (76 cm) row spacing? (ii) Is there a yield increase for narrow row production? The study was planted in a split‐plot randomized complete block design with four replications. The whole plot factor was row spacing, and the subplot factor was hybrid. Two hybrids (P0506AM and P0604AM) were in an “early”‐season group, and two hybrids (P1197AM and P1443AM) were “full”‐season hybrids. Both P0506AM and P1443AM were identified as AQUAmax hybrids and had superior seed company drought tolerance ratings over their maturity pairing counterpart. Grain and forage yield were 4% and 8% greater, respectively, for the narrow row spacing across hybrids. Hybrid differences in drought tolerance designation did not result in grain or forage yield differences under varied row spacings. There was no hybrid × row spacing interaction. In most site‐years, P1197AM hybrid produced the greatest grain and forage yields, though P1443AM and P0506AM were similar in most cases. Results suggest a minor advantage in yield (≤8%) from narrow rows in Ohio and Pennsylvania, though other considerations that include cost to conversion should be considered prior to adoption.

Intraspecific competition in row spacings in soybean

The aim of this study is to assess the impact of various row spacings on the morphology, components of grain yield, and overall grain yield of soybean. The experiments were conducted over two planting seasons (2014/2015 and 2015/2016) using two planting dates (November and December) and two cultivars, FPS Urano RR and BMX Tornado RR. The row spacings tested were: 45 cm (wide row), 45 × 45 cm (cross row), 22.5 × 45 cm (twin row), and 22.5 cm (narrow row). Measurements included leaf area index and sunlight interception at R2 stage, as well as grain yield components and overall grain yield. Narrow rows, in addition to achieving canopy closure, also demonstrated enhanced sunlight interception at the R2 stage. However, the positive effect of increased sunlight interception on grain yield was only significant for the December planting date, with no notable difference observed for the November planting date. These findings imply that while narrow rows may offer advantages, particularly in later planting dates, their implementation should be carefully considered and may not consistently lead to increased grain yield, reinforcing the continued preference for conventional row spacing.

Effect of Row Spacing and Plant Density on Silage Maize Growth, Dry Matter Distribution and Yield

Maize growth in narrow rows provides a more uniform spatial arrangement, but it does not always lead to increasing yield. A four-year study was conducted to investigate the effect of row spacing on silage maize growth and yield during the growing season and at harvest time. A field experiment with conventional (0.70 m) and narrow rows (0.35 m) at a plant density of 92,000 plants ha−1 was evaluated in the years 2011–2014, and the interaction of row spacing × plant density (92,000 and 110,000 plants ha−1) was tested in 2013–2014. The narrow rows clearly demonstrated potential to support plant height and weight development, together with a higher stalk proportion, at around two months after seeding. However, these contrasts were lost in the later stages and at harvest time. Some potential for non-significantly higher dry matter yield (4.6–10.8%) was shown in the narrow rows in three years of the experiment, in association with lower losses in plant numbers, when compared to conventional row spacing. The potential of yield improvement in the narrow rows showed relationships with weather conditions during the second half of the growing season. In summary, under the growing conditions of the study region, narrow row spacing significantly promoted early plant development, but these effects did not persist until harvest, thus resulting in only limited success in yield improvement.

Influence of plant spatial arrangement and water supplementation on soybean productivit

The present study aims to evaluate the influence of plant spatial arrangement and water supplementation on soybean yield for the 2020/21 crop year, in the edaphoclimatic conditions of the central region of Rio Grande do Sul (Brazil). The field experiment was installed in an experimental area of ​​ the Rio Grande do Sul State University (UERGS) in the city of Cachoeira do Sul. Supplementary irrigation provided positive increases in soybean yield between 13% (row spacing of 0.75 m) and 35% (row spacing of 0.50 m). The conventional row spacing of 0.50 m can be recommended as a spatial arrangement strategy for both irrigated areas (productivity 5,196.6 kg ha-1) and rainfed areas (productivity 3,360.0 kg ha-1), optimizing costs regarding the mechanization of farming.

Exogenous application of bio-stimulant and growth retardant improved the productivity of cotton cultivars under different planting arrangement.

Optimum planting arrangement is an important attribute for efficient utilization of available resources and to obtain high yield of cotton. Application of plant growth promoter and retardant on cotton in improved planting density are the innovative techniques in the establishment of more productive cotton crop. Therefore, we planned a field study to assess the role of bio-stimulant and growth retardant in the resource utilization efficiency of cotton cultivars planted under variable row spacing at Agronomic Research Area Bahauddin Zakariya University and Usmania Agricultural Farm Shujabad during Kharif 2012. Experimental treatments consisted of cotton genotypes viz. CIM-573 and CIM-598, cultivated under conventional (75 cm), medium (50 cm) and ultra-narrow row spacing (25 cm) with foliar spray of bio-stimulant (moringa leaf extract) and growth retardant (mepiquate chloride), either sole or in combination, keeping distilled water as a control. Exogenously applied MLE alone and MLE + MC significantly enhanced the number of squares, flowers and green bolls per plant leading to higher cotton seed and lint yield of CIM 598 cultivar cultivated under conventional row spacing. While application of MC alone and MLE + MC produced maximum micronaire value, fiber strength and fiber uniformity ratio of CIM 573 cultivar cultivated under conventional row spacing. The results suggested that application of MLE is a possible approach to enhance the cotton productivity and the use of MC to enhance the fiber quality attributes under conventional row spacing.

Resource use efficiency of cotton in improved vs conventional planting geometry with exogenous application of bio-stimulant and synthetic growth retardant.

Plant growth regulators and improved planting density are the innovative techniques in the establishment of more productive cotton crop. A field study was planned to assess the role of growth regulators in the resource utilization efficiency of cotton cultivars under different row spacing at Agronomic Research Area, Bahauddin Zakariya University Multan and Usmania Agricultural Farm, Shujaabad during Kharif 2012. The study was comprised of cotton cultivars viz. CIM-573 and CIM-598, cultivated under conventional (75 cm), medium (50 cm) and improved ultra-narrow row spacing (25 cm) and foliar spray of growth regulators viz. moringa leaf extract (MLE) and mepiquat chloride (MC), either alone or in combination, distilled water as a control. The application of MLE alone and in combination (MLE + MC) showed the promoting effect on crop growth rate, net assimilation rate, leaf area index, leaf area duration, sympodial branches and number of bolls leading to higher seed cotton yield of both cotton cultivars grown under conventional row spacing. While application of MC averts the plant growth without considerably improving the productivity. MLE being rich source of growth promoting hormone and nutrients showed its potential to a far greater extent under conventional row spacing in efficient utilization of available resources compared to MC and distilled water.

Poultry Litter and Cover Crop Integration into No‐till Cotton on Upland Soil

Core Ideas Applying poultry litter to the top of cover crop residue increased lint yield in drier years.This practice enhanced cotton lint yield, soil C, and soil health.This practice reduced NO3–N and water‐soluble P by 49 and 22% in 5‐cm soil depth, a zone of plant–soil–water interactions. The influence of poultry litter (PL) and cover crops have under no‐till cropping systems in Mississippi upland soils on cotton (Gossypium hirsutum L.) yield and subsequent soil health are largely unknown. A 4‐yr field study was conducted to determine the effect of winter wheat (Triticum aestivum L.) cover crop and PL on cotton lint yield in narrow (0.75 m) and conventional (1.01 m) row spacings. The experimental design was split‐split plot with three replications. The cover crop treatment was assigned to the main plots. Within the cover crop treatment, a narrow row spacing compared to conventional row spacing as subplots. Fertilization treatments included unfertilized control, inorganic N fertilizer (112 kg N ha−1) and PL (6.7 Mg ha−1). Lint yield was significantly greater with PL than inorganic fertilizer each year. Lint yield in a dry season was significantly greater with cover crop treatment. However, following the cessation of PL in 2017, lint yield increased by 12% in the absence of cover crop residue. As compared to unfertilized control, applying PL in the presence of cover crop residue enhanced soil C by 22% and water aggregate stability by 7.4% and reduced soil penetration resistance and bulk density by 9 and 3.5%, respectively. Applying PL for 3 years increased soil levels of both gram‐negative bacteria, 16S rRNA, and ureC, while planting cover crop doubled heterotrophic plate count bacteria. Integration of PL and cover crop residue in a no‐till cotton increased lint yield and improved soil quality indicators.

Skip row planting configuration shifts grain sorghum water use under dry conditions

Grain sorghum (Sorghum bicolor L. [Moench]) is grown as a dryland crop in the semi-arid Central Great Plains. Growing the crop in a skip row configuration has been proposed as a means of delaying water use during the vegetative stage such that more water will be available to be used during the more critical flowering and grain filling stages, thereby improving yield under water stress conditions. The objective of this study was to determine if grain sorghum grown in a skip row configuration used water differently than sorghum grown in conventionally spaced rows. Grain sorghum was grown for three years at Akron, CO in three planting configurations: conventionally spaced rows 0.76 m apart, one row planted and one row skipped (P1S1), and two rows planted and two rows skipped (P2S2). Each planting configuration was planted at two seeding rates. Soil water was measured at several distances from the planted row at planting, flowering, and physiological maturity. Soil water depletion and water use were not affected by seeding rate. Grain sorghum was found to extract water at distances of 114 cm from the planted row. When growing season conditions were dry and starting soil water contents were low, skip row planting shifted the water use such that greater water use was seen during the second half of the growing season than with the conventionally spaced planting. These results support the observation of greater sorghum yields with skip row planting than with conventional row spacing during dry growing seasons.Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for com-munication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Direc-tor, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.

Planting Geometry Effects on the Growth and Yield of Dryland Cotton

The declining Ogallala Aquifer beneath the Southern High Plains may necessitate dryland crop production and cotton (Gossypium hirsutum L.) is a well-adapted and potentially profitable alternative crop. The limited growing season duration of the Texas Panhandle and southwestern Kansas, however, imposes significant production risk due to incomplete boll maturation. Emphasizing earlier boll production that is usually confined to sites on lower fruiting branches may reduce risk, but offsetting high planting densities are needed to maintain desirable lint yield. Our objectives were to quantify planting: 1) row width and 2) in-row spacing effects on growth, yield, and fiber quality of dryland cotton. Field tests of row widths from 0.25 to 0.76 m and plant densities with in-row spacing ranging from 0.075 to 0.15 m were conducted from 1999 to 2005 on a nearly level Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll) managed in a wheat (Triticum aestivum L.), cotton, fallow (W-Ctn-F) rotation. To expand the basis of comparison, cotton growth and yields were simulated using GOSSYM and long-term (1958-2000) weather records from Bushland, TX, as input for all combinations of 0.38 or 0.76 m row widths and plant spacing of 0.075, 0.10 and 0.15 m. Experimental and computer simulated plant height and harvested boll number increased significantly with increased row spacing and, occasionally, in-row plant spacing. Modeled lint yield for 0.38 m rows decreased by approximately 50% compared with the 582 kg·ha-1 yield for conventional row spacing, which was practically duplicated by field observations in 2001 and 2004. Measured fiber quality occasionally improved with conventional row spacing over ultra-narrow rows, but was unaffected by plant spacing. Because narrow rows and frequent plant spacing did not improve lint yield or fiber quality of dryland cotton, we do not recommend this strategy to overcome a thermally limited growing season.

<b>Effect of foliar fungicide and plant spacing on the expression of lipoxygenase enzyme and grain rot in maize hybrids

This study was carried out with the objective of evaluating the effect of fungicide application on grain rot in commercial maize hybrids and the relation between grain rot and the expression of lipoxygenase enzyme in grain in conventional row spacing of 0.70 m and reduced row spacing of 0.45 m. Treatments were made in a 3 x 8 factorial scheme, using three forms of management with fungicide (Trifloxystrobin + Prothioconazole) and eight maize hybrids divided into two groups (tolerant and susceptible) with three repetitions, totaling 72 plots in each environment (conventional and reduced spacing) in the 2013/2014 crop. The following characteristics were evaluated: grain rot percentage and lipoxygenase enzyme expression (LOX) in the grain. The hybrid and the fungicide utilized influenced the grain rot percentage. Grain rot percentage was reduced by the use of the fungicide, and the highest reduction was in susceptible hybrids with two applications, V8 and V8+VT. There was higher expression of LOX enzyme in maize hybrids that belong to the group tolerant of fungi that cause grain rot .The use of the fungicide in two applications, V8 (eight leaves) and VT (tasseling), increased the intensity of the LOX enzyme, which was more evident for the reduced spacing.

Canopy Apparent Photosynthetic Characteristics and Yield of Two Spike-Type Wheat Cultivars in Response to Row Spacing under High Plant Density.

In northern China, large-spike wheat (Triticum aestivum L) is considered to have significant potential for increasing yields due to its greater single-plant productivity despite its lower percentage of effective tillers, and increasing the plant density is an effective means of achieving a higher grain yield. However, with increases in plant density, the amount of solar radiation intercepted by lower strata leaves is decreased and the rate of leaf senescence is accelerated. Row spacing can be manipulated to optimize the plant spatial distribution under high plant density, therefore improving light conditions within the canopy. Consequently, field experiments were conducted from 2010 to 2012 to investigate whether changes in row spacing under high plant density led to differences in canopy apparent photosynthesis (CAP), individual leaf photosynthesis and grain yield. Two different spike-type winter wheat cultivars, Jimai22 (a small-spike cultivar as a control cultivar) and Wennong6 (a large-spike cultivar), were grown at a constant plant density of 3,600,000 plants ha–1 (a relatively higher plant density) over a wide range of row spacing as follows: 5-cm row spacing (R0), 15-cm row spacing (R1), 25-cm conventional row spacing (R2), and 35-cm row spacing (R3). The two-year investigations revealed that increased row spacing exhibited a significantly higher light transmission ratio (LT), which improved light conditions within the canopy; however, excessive light leakage losses in R2 and R3 treatments were not favorable to improved irradiation energy utilization efficiency. Aboveground biomass accumulation was influenced by row spacing. Two spike-type wheat accumulated greater biomass under 15-cm row spacing compared to other row spacing treatments, although a markedly improved photosynthetic rate (PN), effective quantum yield of photosystem II (ΦPSII) and maximal efficiency of photosystem II photochemistry (Fv/Fm) in the penultimate and third leaves were observed in R2 and R3 treatments. At the same time, a longer duration of CAP and green leaf area was maintained in R1 during grain filling. Compared with conventional row spacing, Wennong6 in R1 treatment obtained 21.0% and 19.1% higher grain yield in 2011 and 2012, respectively, while for Jimai22 it increased by 11.3% and 11.4%, respectively. A close association of yield with CAP and LAI at mid-grain filling was observed. In conclusion, for the tested growing conditions, decreasing the row spacing to an optimal distance (15 cm) maintained a longer duration of LAI and CAP during grain filling, made a better coordination of group and individual leaf photosynthesis, and accumulated higher aboveground biomass, leading to a greater grain yield. In addition, Wennong6 had a more rational canopy architecture than Jimai22 (improved LT and higher LAI) and CAP under 15-cm row spacing, leading to a higher grain yield, which indicated that the large-spike type cultivar has the potential to obtain higher yields by increasing plant density through optimum row spacing allocation (15 cm).

Estimation of crop coefficients of dry-seeded irrigated rice–wheat rotation on raised beds by field water balance method in the Indo-Gangetic plains, India

Lack of information on crop coefficient (kc) values of bed planted rice–wheat system in the Indo Gangetic Plains (IGP) of India has become a constraint for irrigation planning to improve the crop water productivity. In this paper, we estimated kc values from field water balance measured crop evapotranspiration (ETc) and Penman–Monteith estimated reference ET0 for dry-seeded irrigated bed planted rice–wheat rotation and also compared with conventional dry-seeded flat system of planting. The experiment was conducted in 2001–2003 at New Delhi, India. Estimated kc values at initial stage (4–6th weeks of sowing) on raised beds were comparable with flat conventional planting for rice but significantly higher for wheat. However, in later stages of growth, kc values for both rice and wheat were lesser on beds than flat land. The kc values of rice during initial, crop development, mid-season and late-season stages on beds were 0.62, 0.75, 1.16 and 0.67, respectively while in conventional flat land, corresponding kc values were 0.61, 0.97, 1.42 and 0.91, respectively. The kc values for wheat at four crop growth stages (initial, crop development, mid- and late-season) on raised beds were 0.98–1.06, 1.10–1.14, 1.25–1.26 and 0.46–0.47, respectively while on flat land with conventional row (20cm) spacing, corresponding kc values were 0.87, 1.12, 1.45 and 0.55, respectively. Flat beds similar spacing (20–47cm) with raised beds had comparable kc values. Bed geometry led variation in plant population density influenced strongly both crop ETc losses as well as kc values. The results provide estimates of ET0, ETc and kc for use in irrigation scheduling in bed planted rice–wheat system in the IGP of India and elsewhere with similar environmental conditions.

Interactions between climate change and sugarcane management systems for improving water quality leaving farms in the Mackay Whitsunday region, Australia

Nitrogen (N) lost from cropping is one of the major threats to the health of the Great Barrier Reef (GBR) in northern Australia, and there are government initiatives to change farming practices and reduce N losses from farms. Sugarcane is the dominant crop in most catchments draining into the GBR lagoon, especially those of the Mackay Whitsunday region (8400km2) where sugarcane represents>99% of cropping in the catchments, and is grown with large applications of N fertiliser. As farmers and farming systems adapt to a future requiring lower environmental impact, the question arises whether climate change may influence the effectiveness of these changes, an issue rarely considered in past water quality studies. To address this question we used the APSIM farming-systems model to investigate the complex interactions between a factorial of five proposed sugarcane management systems, three soil types, three sub-regional climatic locations and four climate change projections (weak, moderate and strong, with historical climate as a ‘control’). These projections, developed from general circulation models and greenhouse gas emission scenarios, estimated that median annual rainfall would be reduced by up to 19%, and maximum and minimum temperatures increased by up to 0.5°C and 0.6°C, respectively. Management practices, such as tillage, fallow management and N inputs, were grouped into five systems according to the perceived benefits to water quality. For example; management System A grouped together zero tillage, soybean rotation crops, reduced N inputs and controlled traffic practices. While at the other end of the scale, System E included many severe tillage operations, bare fallows, high N inputs and conventional row spacing; practices that are still used in some areas. Importantly, this study parameterised controlled traffic systems, which is considered an important component of ‘best’ management in the GBR catchment, but for which water quality benefits have yet to be widely quantified. The study predicted that the improvement in farm management needed to meet water quality improvement goals will not be greatly affected by climate change. However, without any interventions, the frequency of years with very high N losses, and hence extreme ecological risk, was predicted to increase by up to 10–15%. Compared with traditional practices, improved management systems were predicted to reduce N losses by up to 66% during these years. The results support continued adoption of improved management systems to achieve proposed water quality targets in both the current and a range of potential future climates. However, there are important uncertainties about the effects of elevated atmospheric CO2 concentration on plant assimilation rates and the characterisation of extreme climate events that deserve further study.

Configurações de semeadura e produção e qualidade da fibra do algodoeiro

We evaluated, in two locations, production and fiber quality of cultivar IAC 23 cotton plants in ultranarrow row, narrow row and conventional row spacing, varying number of plants by linear meter. Two experiments had been lead, one in Piracicaba – SP and another one in Campinas – SP, both in the crop year 2001/02. The experimental design was randomized blocks, in a factorial scheme, with 4 replications, being three spacing rows: 0.38m (ultra-narrow), 0.76m (narrow), and 0.95 m (conventional); and four densities (5, 8, 11, and 14 plants by linear meter). In Piracicaba, the production of cotton was 12% and 8,4 % superior in the ultra-narrow row and narrow row, respectively, when compared to the conventional row. In the ultra-narrow row in the smaller density of plants in the line, the production of cotton was 29.2% and 22.3% superior, respectively, to the productions of the narrow row and conventional row in the same number of plants in the line. The smaller spacing and higher plant density on the line, the smaller the number of bolls per plant at both locations. The agronomic characters of laboratory and the technological characteristics of the fiber were not modified by the populations of plants in the two studied environments.

Presidedress Soil Nitrogen Test for No‐Tillage Maize at Different Row Spacing

A presidedress soil nitrate test (PSNT) can be used to evaluate preplant N applications as a complementary method to N budget in maize (Zea mays L.) under different management practices. Narrow rows have shown increased N accumulation and recovery efficiency by maize, and therefore soil NO3−–N critical concentration (CC) for maximum yield could be lower than in conventional row spacing. An experiment was performed at Balcarce (Argentina) in 1996–1997, 1999–2000, and 2000–2001 to evaluate the PSNT for irrigated no‐till (NT) maize with different row spacings (70, 52, and 35 cm) and N rates (0, 90, 140, and 180 kg N ha−1). Soil samples were collected to a 30‐cm and 30‐ to 60‐cm depth when maize was at the six‐leaf stage (V6). Grain yield was significantly increased by narrow rows mainly at low N availability. Relative yield was highly associated (r2 = 0.73 and 0.68) with soil NO3−–N concentration (0–30 cm) at V6 for conventional and narrow rows, respectively. Soil NO3−–N concentration for maximum yield (95%) was greater for conventional row spacing (22 mg kg−1) compared with narrow rows (17 mg kg−1). The reliability of the PSNT (r2) did not improve when sampling was done up to a 60‐cm depth. These results confirm the hypothesis that the NO3−–N CC determined for the PSNT is lower for maize crops growing in narrow rows than conventional row spacing. Narrow rows maize is a simple management practice that could contribute to enhancing system sustainability.

Yield and water productivity of rice–wheat on raised beds at New Delhi, India

Permanent raised beds are being proposed for the rice–wheat system in the Indo-Gangetic Plain to increase its productivity and to save water. It is not clear whether reported water savings in rice arise from the geometry of the beds per se or from the particular water management that keeps the soil in aerobic conditions and that can also be applied on flat land. Moreover, little research has been reported on direct seeding of rice on raised beds and on the effect of raised beds on the subsequent wheat crop. In this paper we compare the yield, input water (rainfall and irrigation) use and water productivity of dry-seeded rice on raised beds and flat land with that of flooded transplanted and wet-seeded rice, and analyze the effects of beds on the subsequent wheat crop. The experiment was conducted in 2001–2003 at New Delhi, India. Rice yields on raised beds that were kept around field capacity were 32–42% lower than under flooded transplanted conditions and 21% lower than under flooded wet-seeded conditions. Water inputs were reduced by 32–42% compared with flooded rice, but could also be accomplished with dry seeding on flat land with the same water management. Reduced water inputs and yield reductions balanced each other so that water productivity was comparable among most treatments. Wheat yield was 12–17% lower on raised beds than on flat land with conventional (20 cm) row spacing. Neither wheat nor rice on raised beds compensated for the loss in rows by extra tillering or leaf growth at the edges of the rows. There was no carry-over effect of type of land preparation in rice on the growth and yield of the subsequent wheat crop. Further research on raised beds should focus on the selection of suitable rice and wheat varieties, soil health issues such as nematodes and micro-nutrient deficiencies, weed control, bed stability and long-term carry-over effects from one crop to the other.

Nitrogen Fertilization and Yield of Cotton in Ultra‐Narrow and Conventional Row Spacings

Nitrogen fertilizer requirements of ultra‐narrow row (UNR) cotton (Gossypium hirsutum L.) are not well established, and lint yield of UNR relative to conventional‐row (CR) cotton has been variable. Objectives of this study were to compare UNR and CR N requirements based on lint yield, fiber quality, and plant architecture, and to compare the yield potential of UNR and CR cotton. The location was the Texas Agricultural Experiment Station Farm, Burleson County, TX. Treatments were N fertilizer rates of 0, 50, 101, and 151 kg ha−1 and row spacings of 19, 38 (both UNR), and 76 cm (CR). By design, per‐hectare plant populations were greatest in 19‐ and least in 76‐cm row spacings. Plots were hand harvested. Reductions in row spacing decreased plant height, main stem nodes plant−1, and subset (first position bolls at nodes 6–10) individual boll weight. Greater N increased plant height, main stem nodes plant−1, and both whole‐plant and subset individual boll weight. Lint percentage was increased by reduction in row spacing and not affected by N. Treatment effects on fiber quality were limited. Lint yield did not differ among row spacings. Significant increases in lint yield occurred with each increase in N, suggesting that the optimal N rate was not surpassed. Nitrogen by row spacing interaction on lint yield was not significant, implying a similar response of each row spacing to N over the fertilizer rates tested. The N fertilizer requirements of UNR do not appear to be lower than those of CR cotton.

Effect of row spacing and herbicide dose on weed control and grain sorghum yield

Field studies were conducted in 2000 and 2001 near Yoakum, Texas without irrigation to determine the effect of row spacing and herbicide dose on weed control and grain sorghum response. Atrazine or dimethenamid alone or in combination were compared under conventional row spacing (single rows spaced 91 cm apart on a bed) and twin rows (two rows spaced 20 cm apart on a single bed). Amaranthus albus (tumble pigweed) control was 100% with all treatments except dimethenamid at 0.56 kg/ha which controlled at least 96%. Panicum texanum (Texas panicum) control was less than 80% with dimethenamid at 0.56 kg/ha and atrazine at 0.56 and 1.12 kg/ha under the conventional row spacing. Under the twin-row system, P. texanum control was greater than 80% with all herbicides. Cyperus esculentus (yellow nutsedge) control was less than 70% early season with both row spacings but greater than 80% late season under the twin-row system.

Phosphorus fertiliser placement for lupins in southern New South Wales

Research in Western Australia and South Australia indicated that fertiliser phosphorus (P) banded below the seed of narrow leaf lupin (Lupinus angustifolius L.) at sowing was a more effective method of applying P�fertiliser than the usual placement of P with the seed. This technology has not been investigated in southern New South Wales where lupins have been known to be unresponsive to fertiliser P.We conducted 4 field experiments to examine the effect on lupin yield of applying 6 rates of P (0, 5, 10, 15, 20 and 40 kg/ha) either by placement with or below the seed. To further test responsiveness to P, an additional set of treatments was used; applying P at 40 kg/ha before sowing and then placing additional P below the seed at the 6�rates of application. The grain yield of lupin was increased by P application at all sites, despite the medium to high P�status of 3 of the 4 sites used in these experiments. However, the technique of banding P fertiliser below the seed depth rather than placing it in direct seed contact had only a small advantage in grain yield responsiveness to applied fertiliser P (P = 0.09). Fitted response curves indicated that when P was applied at 15 kg/ha, grain yield increased by 60 kg/ha at one site and 30 kg/ha at the other 3 sites, if P was deep-placed rather than applied in seed contact. This advantage of deep placement of P fertiliser was much smaller than has been reported in Western Australia.Placement of P below the seed of lupin when sown on the red earth and red-brown earth soils of southern New South Wales slightly enhanced the availability of fertiliser P. This applied even when sowing was quite shallow (2–3�cm), provided recommended rates of P fertiliser were used at conventional row spacing (17 cm). Separation of seed and fertiliser to avoid reduced germination may be an advantage when using double row spacing and higher P�application rates.

Phenotypic Alterations and Crop Maturity Differences in Ultra‐Narrow Row and Conventionally Spaced Cotton

Ultra‐narrow row cotton (Gossypium hirsutum L.) production is considered a potential strategy for reducing production costs by shortening the growing season. A 2‐yr field study was conducted near College Station, TX, on varying soil types to document phenotypic alterations and crop maturity differences for cotton grown in 19‐, 38‐, 76‐, and 101‐cm row spacings. In the 19‐cm rows, the plant densities were 12.2, 18.8, and 40.5 plants m−2 Densities of 11.3 and 19.5 plants m−2 were established in the 38‐cm rows. In the 76‐ and 101‐cm rows, plant densities of 11.7 and 7.4 plants m−2, respectively, were evaluated. Plant height and node counts were reduced in the narrow (19 and 38 cm) row spacings in only 1 yr. The narrow row spacings at the higher plant densities consistently accumulated leaf area index more rapidly than the conventional (76 and 101 cm) row spacings. In 1998, when the study was conducted on a heavy clay soil, the higher plant densities in the 19‐ and 38‐cm row spacings tended to partition more biomass to reproductive structures and yielded more than the conventional row spacings. In 1999, the test was conducted on a lighter silty clay loam soil and yields were unaffected by the row‐spacing treatments. In 1998, the higher plant densities in the 19‐ and 38‐cm row spacings had a greater percentage of harvestable bolls at the first fruiting positions on lower nodes, a boll distribution pattern that contributed to earlier crop maturity. Narrow row spacings and high plant densities did not consistently alter fiber quality. No conclusive differences for crop growth and development could be ascertained between the medium and high plant densities in the 19‐ and 38‐cm row spacings. However, ultra‐narrow row cotton may be more advantageous to producers when grown on heavier soils that typically do not promote excessive vegetative growth.