Cotton response to placement and rate of starter fertilizer

Application of starter fertilizer at‐planting is a convenient method of applying phosphorus (P) and pre‐plant nitrogen (N) to cotton (Gossypium hirsutum L.). In addition, the placement of starter fertilizer in‐furrow requires no extra tanks or pumps, and can be tank mixed with at‐planting insecticides, fungicides, or plant growth regulators. Over a four‐year period, tests were initiated to determine the effect of 10–34–0 starter fertilizer applied in‐furrow and in a 5 cm to the side and 5 cm below the seed placement (5 cm x 5 cm). Lint yields were measured all four years. Stand counts, Chambers’ skip index, and plant heights were measured the final year. Placement of starter fertilizer in‐furrow was shown to decrease yields compared to a 5 cm x 5 cm placement and a check two out of four years. Plant stands, skip indexes and plant heights were adversely affected by an in‐furrow placement as well. A 5 cm x 5 cm placement did not significantly differ in terms of yield in any year from the check. Plant stands and skip indexes were not affected, but plant height was increased over the check with one rate of starter placed 5 cm x 5 cm. Our results suggest that in‐furrow placement of starter fertilizer has the potential to negatively affect seedling growth and decrease yields. A 5 cm x 5 cm placement of starter fertilizer, while it may not increase yields, does not incur these risks and is a safe, convenient and inexpensive method of applying P or pre‐plant N.     

Root mass as a determinant of com hybrid response to starter fertilizer

Many studies have shown variable response to starter or row applied fertilizer on corn (Zea mays L.) hybrids. Field experiments with approximately 25 hybrids over three seasons showed that some hybrids responded to row applied fertilizer with large growth and yield increases while others did not respond. The objectives of this study were to compare root and shoot growth of responsive and non‐responsive corn hybrids to starter fertilizer and their uptake of nitrogen (N) and phosphorus (P). Two glasshouse experiments were conducted with hybrids from the field studies found to be most and least responsive to row applied fertilizers. In the first experiment, P was applied at levels of 0,10,20, or 30 mg kg^‐1 and was mixed with either 25 or 100% of the total soil volume (1.5 L). Nitrogen was mixed with the total soil volume in all treatments at a rate of 100 mg pot^‐1. Phosphorus rates in the second experiment were 0, 30, or 60 mg kg^‐1 and the N rate was 200 mg pot^‐1. Fertilizer N and P were mixed with total soil volume or banded 5 cm below the soil surface and 5 cm away from seed. The soil was obtained from the A horizon of Norfolk loamy fine sand (fine loamy, siliceous, thermic, Typic Kandiudult). Time from seeding to harvest was 33 days for the first experiment and 41 days for the second. Root weight of the non‐responsive hybrid was 31 % higher in the first experiment and 48% higher in the second than of the responsive hybrid. Each hybrid responded similarly to starter P (62 to 78% increase in top growth). The responsive hybrid produced a significant (P 0.05) increase in top (92%) and root (76%) weight due to starter N, but the non‐responsive hybrid did not respond to N placement. The lack of response to starter N‐fertilizer was attributed to greater root growth in the non‐responsive hybrid because its top and root weight with broadcast N were about the same as those of the responsive hybrid with banded (starter) N. Since the hybrids differed only in response to starter N, a convenient method to classify corn hybrids with respect to starter fertilizer response is to measure top growth at six weeks after planting with banded versus broadcast N applied at planting.     

Response of burley tobacco to banded fertilizer and in‐row subsoiling

Abstract

Field experiments were conducted during 4 years at two locations in Kentucky to study the response of burley tobacco to phosphorus (P) and potassium (K) fertilizer rate and placement, and to in‐row subsoiling. In one experiment on Pope soil (mesic Fluventic Dystrochrepts), dry matter and P and K uptake 40 days after transplanting, and cured leaf yield and value/ha were increased as application of a 5–13–36 (%N‐P₂O₅‐K₂O) grade fertilizer increased from 310 to 930 kg/ha. Generally, fertilizer placed in 40‐cm wide bands directly under and parallel to the row was more effective than broadcasting and in‐row subsoiling was more effective than not subsoiling. Significant 2‐way and 3‐way interactions suggested that plant responses to band applications over broadcasting were greater in the presence than absence of subsoiling. In another experiment conducted on two silt loam soils, Pope and Maury (typic Paleudalfs), fertilizer applied in a 40‐cm band with in‐row subsoiling was more effective than broadcasting without subsoiling or placement in 10‐cm wide bands applied 0.6‐m apart and perpendicular to the row without subsoiling. Growth and yields increased up to the 620 kg/ha rate and 40 days after transplanting, soil pH decreased and soil electrical conductivity and plant manganese (Mn) increased with increased rate of fertilizer.     

Starter fertilizer and the method and rate of potassium fertilizer effects on cotton grown on soils with and without winter grazing by cattle

Abstract

A three‐year field study was conducted on a Decatur silt loam (clayey, kaolinitic, thermic Rhodic Paleudult) in North Alabama. The objective of the study was to evaluate the effects of winter grazing by cattle on the potassium (K) and starter fertilizer needs of cotton (Gossypium hirsutum L.) the following season. Grazed and non‐grazed treatments were established by planting a wheat (Triticum aestivum L.) cover crop in the fall and allowing cattle to graze half of the treatment area for 35 to 65 days in late winter‐early spring. After grazing, the grazed and non‐grazed wheat was killed and cotton was planted using a strip‐tillage system. Test areas had medium to high soil test ratings for K. Fertility treatments consisted of three rates of K (0, 37, and 74 kg K ha^‐1), three methods of K application (surface broadcast; in‐row, band application at a depth of 30.5 cm; and surface banding using a spacing of 50.8 cm) and two rates of starter fertilizer (no starter and 168 kg#lbha^‐l of a liquid 15–15–0). Seed cotton yields were affected by grazing of the winter cover crop prior to planting, but not by the method of K fertilizer application. During the two years that a yield reduction was observed, winter grazing reduced seed cotton yields by an average of 14%. Cotton responded to K rate only under the ungrazed system. During the first and second year of the test, an application of 37 kg K ha^‐1 increased seed cotton yields by an average of 351 kg#lbha^‐1. Starter fertilizer consistently gave slightly higher yields with a significant response occurring in two out of the three years.     

Quantifying aggregate stability of a clay soil under annual forage crops

This study explored the influence of 10 annual forage legumes belonging to the Lathyrus and Vicia genera on wet aggregate stability (WAS) and dispersion ratio (DR) indices of a clay soil. Five Lathyrus and five Vicia species were sown in autumn. Seed‐to‐seed and row‐to‐row distance was maintained at 5 cm and 20 cm, respectively. The experiment was planned in a randomized block design with three replications. After 90 d following seed harvest, soil cores were collected from two depths (0–15, 15–30 cm) in each plot and WAS and DR were determined. Annual forage legumes increased WAS of the soil but decreased the DR index. The WAS and DR values were affected at level of p < 0.001 by genus, species, and soil depth. Values of WAS and DR of the control plots without plant on the average were found to be 44.5% and 9.3% for 0–15 cm, and 41.2% and 10.1% for 15–30 cm, respectively. For 0–15 cm depth, the highest WAS (77.7%) and the lowest DR (6.4%) values were found in L. sphaericus L. (wild) plots. For 15–30 cm depth, the highest WAS value (62.6%) was obtained in L. annuus L. (wild) plots and the lowest DR value (6.7%) was in L. sativus L. (Gurbuz‐2001) plots.     

Soybean growth and yield response to residual fertilizer phosphorus bands

Residual effects on soybeans (Glycine max L.) from phosphrous (P) fertilizer bands applied 5 cm to the side and 5 cm below the seeds of a preceding corn (Zea mays L.) crop on a Brandt silt loam soil (fine‐silty, mixed Udic Haploboroll) were studied after an intervening no‐till fallow period. The P rates applied were 0, 12, 24, and 49 kg P ha^‐1. Soybean rows were planted as close as possible to the preceding corn rows. Soybean tissue was sampled at the early bloom stage in each row of the paired‐row design. Twenty soil column (2.5x3 cm) samples were collected from the 0–15 cm depth along a 50‐cm‐long trench that bisected a soybean row. The distance of the previous P band (column with the highest extractable Bray‐I P level) from the soybean row became a variable in this experiment with category range distances of <6 cm, 6–9 cm, and >9 cm from band to row. Residual P from all application rates increased shoot dry matter weight, shoot P uptake, and to a lesser extent grain yield in comparison to the unfertilized soybeans. Distance of the P band from the row was more important than the P concentration in the band. Shoot P uptake and grain yield were significantly larger for fertilized compared to unfertilized soybeans when the band distance was less than 9 cm from the row. Residual P band distance of greater than 9 cm from the row had little effect on soybean growth and yield.     

滴施不同水溶性磷肥对石灰性土壤磷分布及玉米磷素吸收利用的影响

  【目的】  磷的形态影响着其施入土壤后的移动分布。研究滴灌施肥中不同水溶性磷肥在石灰性土壤中的分布特征及玉米对磷素的吸收和利用,为滴灌玉米生产中的磷肥选择提供理论依据。  【方法】  于2018—2020年在新疆石河子市实验站开展滴灌玉米田间试验,选用玉米品种‘郑单958’作为试验材料。试验共设磷酸脲(UP)、磷酸二氢钾(MKP)、聚磷酸铵(APP)、磷酸二铵(DAP)、磷酸一铵(MAP)、不施磷肥(CK) 6个处理,除CK不施磷肥外,其余处理灌溉量及氮磷钾投入量均相同。玉米开花期和成熟期,分别在滴头下、根系、宽行3个位点,在垂直方向0—10、10—20、20—40 cm处采集土样,测定pH、速效磷和全磷含量。采集玉米地上部植物样品,测定茎、叶、穗器官磷素含量。在完熟期测产,计算磷肥利用效率等指标。  【结果】  与DAP和CK处理相比,UP处理能显著降低0—40 cm土层土壤pH,开花期UP处理土壤pH较CK和DAP分别降低了0.20和0.32个单位,成熟期分别降低了0.24和0.31个单位,MAP、APP和MKP也不同程度地降低了滴头下0—10 cm土层土壤pH。UP处理土壤有效磷在0—40 cm土层的分布最均匀,APP处理10—20 cm土壤速效磷含量显著高于UP和MAP。玉米开花期APP、UP、MAP处理土壤速效磷含量较DAP分别增加了65.47%、44.18%和23.14%,成熟期分别增加了58.08%、40.13%和127.89%。APP处理的玉米穗、叶和总磷素积累量均最高,开花期较DAP分别显著增加了29.22%、43.97%和22.43%,成熟期较DAP分别增加了65.39%、26.63%和50.60%。APP、UP、MAP处理的玉米产量没有显著差异,较DAP分别增产了18.03%、11.64%和9.46%,磷肥利用率分别较DAP增加了29.62个百分点、13.65个百分点和9.93个百分点。APP处理的磷肥偏生产力和磷肥农学效率分别较DAP增加了18.03%和174.96%。相关分析表明,玉米产量和磷素积累量与0—20 cm土层的土壤有效磷含量正相关,与20—40 cm土层土壤速效磷含量负相关或相关性较弱。  【结论】  速效磷的分布与土壤pH的变化高度一致。酸性水溶性磷肥可不同程度地降低玉米根系周围土壤pH,磷酸脲的影响范围可达滴头周围0—40 cm土层,磷酸二氢钾、聚磷酸铵和磷酸一铵仅在滴头周围0—10 cm土层范围内有影响,而磷酸二铵对土壤pH无显著影响。滴施磷酸脲土壤中速效磷在0—40 cm土层中的分布较均匀,其在10—20 cm土层中的速效磷含量低于聚磷酸铵并高于其他磷肥处理。磷肥利用率与10—20 cm土层速效磷含量极显著相关。因此,滴施聚磷酸铵的玉米产量和磷肥利用率高于其它磷肥处理。综合3年试验结果,在新疆滴灌玉米生产中,水溶性磷肥中以聚磷酸铵最优,其次是磷酸脲和磷酸一铵等酸性磷肥,应减少磷酸二铵等碱性磷肥的施用。     

Effects of 30 years of cropping and tillage systems on surface soil test changes

Abstract

A common belief is that no‐till systems with adequate fertility will improve soil quality over other tillage systems. The objectives of this study were to determine if crop phase, tillage systems, and n rate in a long‐term rotation affected soil chemical analyses in the surface 15 cm of soil and to evaluate the trend in chemical analyses. To test this hypothesis, surface soil samples were taken from a long‐term (30‐year) cropping and tillage study. This study was initiated in 1965 on a Harney silt loam soil in Central Kansas with every phase of the wheat‐sorghum‐fallow (WDF) rotation included each year. Tillage systems included clear‐till (CT), reduced‐till (RT), and no‐till (NT). In 1975, four nitrogen (N) rates (0, 22, 45, 67 kg N ha¹) were incorporated by subdividing the tillage plots. Topdressed N, as ammonium nitrate, was the only fertilizer added throughout the duration of the study. Soil samples were taken at depths of 0 to 7.5 and 7.5 to 15 cm in all plots in 1965 and in 1995. In 1998, soils on 1997 sorghum plots were samples in 2.5‐cm increments to 15 cm. Samples from all dates were analyzed for pH, available phosphorus (AP), and organic matter (OM), and deviations from the controls from 1965 to 1995 were assessed by subtracting 1995 results from 1965 results. The change in soil pH showed a crop phase by sample depth interaction. In the wheat phase, pH in the top 7.5 cm increased by 0.19 and increased by 0.28 in the 7.5–15 cm layer. In the fallow phase, pH increased by 0.04 and 0.35 in the top 7.5 cm and 7.5–15 cm layers, respectively. The pH change for sorghum was intermediate for both depths. The increase in overall pH from 1965 to 1995 was unexpected and contrary to normal expectations of a decrease over time. Soil OM was not changed significantly over the 30 years of the study, suggesting that OM buildup or depletion is very slow under this cropping system on a nearly level soil with minimal soil erosion. Increasing the rate of N application significantly reduced pH in the upper increment samples, but had little effect on pH below 10 cm. The NT system had the lowest surface increment in pH, but differences among tillage systems were minimal below 7.6 cm. The AP was highest for NT in the surface increment, but for CT at deeper depths. Likewise, OM was highest for NT in the 2.5 cm increment and the CT at deeper increments. Under the present N management, pH may reach levels where herbicide effectiveness and phosphorus availability could be affected adversely. Deep tillage by one‐way or mold‐board plowing might be an interim solution to raise the pH before liming is implemented or P fertilizer is added to maintain adequate AP throughout the top 15 cm. Nitrogen management may need to be changed to some form of band‐type placement to reduce the total N applied. Under the conditions of this study (WSF, reduced tillage, and 57 cm annual precipitation), soil OM increased very slowly.     

Response of no‐tillage and conventional‐tillage cotton to starter fertilization on loess soils

Starter fertilizers have been utilized to improve cotton (Gossypium hirsutum L.) yields, but yield increases have differed with soil type, application method, application rates, and tillage. Starter fertilizer tests were conducted from 1991 through 1993 on a Gigger silt loam (Typic Fragiudalf) in Louisiana and on a Loring silt loam soil (Typic Fragiudalf) in Tennessee to evaluate methods and application rates of 11–37–0 liquid fertilizer for cotton. Treatments were evaluated under conventional‐tillage (CT) and no‐tillage (NT) production systems. Application methods included in‐furrow application at planting (IF), spraying a 4‐inch wide surface band behind the planter (SB), and banding fertilizer two inches to the side and two inches below the seed at planting (2×2). The IF treatments were applied at 1.5, 3.0, and 4.5 gal/A. The SB and 2×2 treatments were applied at 7.5 gal/A. Starter fertilizer treatments were supplemented with broadcast granular fertilizers to achieve a total fertilization rate of 80–40–60 (N‐P₂O₅‐K₂O lb/acre). Starter fertilizer treatments were compared to broadcasting 80–40–60 and 80–0–60. Soil test levels for phosphorus (P) were high on both soil types. In‐furrow applications of 3.0 and 4.5 gal/acre usually reduced plant population for both tillage systems on both soil types. The 1.5 gal/acre IF treatment was less detrimental to stand establishment than the higher IF rates. The effect of starters on plant height varied from year to year. Starter fertilizers usually did not affect early‐season plant height relative to broadcast treatments. In several experiments starter fertilization increased plant height compared to one, but not both, of the broadcast fertilization treatments. High IF rates (3.0 and 4.5 gal/acre) reduced plant height in one experiment. The 2×2 starter fertilizer treatment increased leaf area per plant relative to the broadcast fertilization treatments in two of six experiments on the Gigger soil. Responses for NT and CT studies were similar. In one CT experiment on the Loring soil, the 1.5 gal/acre IF treatment increased leaf area relative to the broadcast treatments. Lint yield responses to starter fertilization were inconsistent. Starter fertilization increased lint yield in one of six experiments on the Gigger soil and in two of six experiments on the Loring soil. Increased yields from starters varied with year and application method, however, the 2×2 and SB treatments tended to provide better responses than IF treatments. Starter fertilizer responses for NT and CT tests were generally similar.     

SOIL QUALITY AND SPATIAL VARIABILITY ASSESSMENT OF LAND USE EFFECTS IN A TYPIC HAPLUSTOLL

Soil management practices can have negative or positive effects on soil quality. Our objective was to assess the effect of long‐term agricultural practices by evaluating selected soil physical and chemical properties. Soil samples were collected from two depths (0 to 15 and 15 to 30 cm) within a native pasture and an adjacent agricultural field that was being used for three different crop rotations. Soil quality was quantified using aggregate stability, bulk density, soil texture and available water content as physical properties and pH, electrical conductivity, organic matter and available phosphorus as chemical properties. The farmland soils were functioning at 71 and 70 per cent of their full potential at the 0‐ to 15‐ and 15 to 30‐cm‐depth increments, respectively, whereas those from the pasture were functioning at 73 and 69 per cent, respectively. The assessment showed substantial loss in soil organic carbon following 50 years of farmland cultivation. Tillage and fertilizer applications were presumably the primary reasons for weaker spatial dependence within farmland at the 0‐ to 15‐cm depth. Grazing was postulated as the main reason for weaker spatial dependence within the pasture soils at the 15‐ to 30‐cm depth. Overall, we conclude that 50 years of cultivation has not caused soil quality to decline to a point that threatens sustainability of the agricultural fields. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of Tillage Systems and Axle Load on Undisturbed Soil Hydraulic Properties

The effects of tillage treatment and axle load resulting from wheeled traffic on tilled soil (0 to 20 cm) were evaluated by measuring the changes in soil physical properties (bulk density and infiltration rate) and by measuring the impact on water retention in comparison with controlled plots. Data obtained from the experimental plots showed that infiltration rate was strongly affected by tillage treatments in 0‐ to 20‐cm depths. Dry bulk density was affected in 0‐ to 20‐cm depths by tillage treatments and axle load. Tillage system changed the ability of the soils to hold moisture and decreased the plant‐available water capacity.     

In-row tillage methods for subsoil amendment and starter fertilizer application to conservation-tilled grain sorghum

Acid subsoils and tillage pans limit crop yields on sandy soils of the Southern Coastal Plain of the United States. Studies were conducted for 3 years on two soils with acid subsoils and tillage pans to determine the effect of starter fertilizer (22 kg N, 10 kg P ha⁻¹ and fluid lime (1350 kg ha⁻¹) placement with in-row tillage methods on growth and yield of grain sorghum (Sorghum bicolor (L.) Moench) grown in a conservation-tillage system. Fertilizer and lime were applied in factorial combinations in the in-row subsoil channel, in a narrow (4-mm) slit 18 cm below the tillage pan (slit-tillage), or 7 cm to the side of the row incorporated 7 cm deep. Slit-tillage was as effective as subsoiling in two of the four tests where plant growth and grain yield responded to deep tillage. Of the other two tests where there was a response to deep tillage, slit-tillage resulted in a 6% decrease in grain yield compared to subsoiling in one test, and an 8% yield increase in the other. Starter fertilizer placement was not critical, but response to starter fertilizer occurred only when deep tillage, either in-row subsoiling or slit-tillage, was used in conjunction with the fertilizer. Starter fertilizer consistently increased early-season plant growth; however, yield response to starter fertilizer was highly dependent on rainfall. Starter fertilizer application increased yield in only one of five tests. There was no benefit from injecting lime.     

Recovery of 15N‐Labeled Nitrate Injected into Deep Subsoil by Maize in a Calcareous Alluvial Soil on the North China Plain

Abstract

Recovery of residual nitrogen (N) from the subsoil by maize (Zea mays L.) was studied by injecting ¹⁵N‐labeled nitrate at 110 cm for treatments with and without N fertilizer in a calcareous soil on the North China Plain. The results show that the recovery of ¹⁵N‐labeled nitrate diffusing in the 90‐ to 130‐cm soil horizon was 11.9% with N fertilizer application and 6.7% without N application in maize. Nitrogen fertilizer applied to topsoil stimulated growth of maize roots in the subsoil, thus increasing the recovery of ¹⁵N‐labeled nitrate. In the relatively dry growing season in this experiment, the ¹⁵N‐labeled nitrate did not move downward because there was no downward water flow at 110 cm. Hence, under dry weather conditions, the maize crop can re‐utilize a small part of the residual soil nitrate in deep soil layers. Most of the nitrogen uptake was in the 0‐ to 80‐cm layer during the experiment.     

Vertical distribution of soluble organic nitrogen,nitrogen mineralization,nitrification, and amidohydrolase activities in a manure‐treated soil

Recent studies indicate that soil soluble organic nitrogen (SON) plays an important regulatory role in the soil–plant N cycle. The aims of this study were to identify the vertical distribution of SON and its correlation with N mineralization, nitrification, and amidohydrolase activities, in a soil repeatedly amended with cow manure or chemical fertilizer. For this purpose, soil samples were collected from 0–20, 20–40, 40–60, 60–80, and 80–100 cm depths of a calcareous soil, which has been annually amended for 5 y with cow manure (CM) at two rates of 50 (CM₅₀) and 100 (CM₁₀₀) Mg CM ha^–1 y^–1. Treatments with chemical fertilizer (CF) and a control (CT) were also included. Soluble organic N, N mineralization, nitrification rates, as well as L‐glutaminase and L‐asparaginase activities were determined. Both CM₅₀ and CM₁₀₀ enhanced SON content throughout the soil profile. Nitrogen‐mineralization rate (N_m) was increased at the 0–20 cm depth of the CM₁₀₀ treatment and remained unaffected at the deeper depths. Nitrification rate (N_n) was significantly higher at the 0–60 cm depth of CM₁₀₀ compared to CF and CT. L‐glutaminase and L‐asparaginase activities were significantly increased at the 0–40 cm depth in both CM₅₀ and CM₁₀₀ compared to CF and CT. The amidohydrolase activities could not be detected below 40 cm, regardless of the fertilizer treatments. Our results suggest that SON makes a minor contribution to N mineralization in deep soil layers. It was also concluded that changes in the SON throughout the soil profile were not associated with changes in the N‐transformation rates (N_m and N_n) and amidohydrolase activities. While we conclude that SON is a major N pool in the whole profile of the manure applied soil further investigation is required to characterize SON and to investigate the bioavailability of SON for microbial activity in different soil depths.     

Sampling depth effects on sodium bicarbonate (NaHCO3)‐extractable phosphorus and potassium and fertilizer recommendations

Abstract

Soil test nutrient concentrations vary with depth, especially in perennial cropping systems where fertilizer is broadcast on the soil surface without incorporation. The objective of this study was to determine the effect of fertilizer rate and sampling depth on soil test phosphorus (P) and potassium (K), and P and K fertilizer recommendations for alfalfa (Medicago sativa L.). Five rates of P and K (0, 56, 112, 224, and 336 kg ha^‐1 P₂O₅ and K₂O) were broadcast on established alfalfa stands at three sites with different soil properties and tillage and fertilization histories. In separate plots at one site the same rates of P and K were also incorporated to a depth of 15 cm prior to seeding alfalfa. Soil samples were collected at depths of 0 to 10, 0 to 15, and 0 to 30 cm during the growing season. Fertilizer rates and soil sample depth affected soil test P and K at all sites. Relative to the 30‐cm sample depth, soil test values were higher in fertilized treatments with 10 and 15 cm sample depths due to the concentration of immobile P and K near the soil surface. Sample depths of 10 and 15 cm frequently resulted in lower P and K fertilizer recommendations than those of the 30‐cm depth. Sample depth is an important consideration in routine soil sampling for the purpose of making fertilizer recommendations. If research data used for developing soil test‐based fertilizer recommendation are obtained using a standard sampling depth, routine sampling must also be to the same depth.     

Mulching With Composted MSW for Biological Control Of Weeds in Vegetable Crops

Compost maturity is one of several issues that the composting industry must face as it attempts to provide a high quality product to the agricultural community. In this paper, we examine the potential for using immature compost prepared from a mixture of municipal solid waste (MSW) and biosolids as a mulch for control of weeds in vegetable crop row-alleys. Two field experiments were conducted with 4 and 8-week-old composts in the fall of 1995 and the spring of 1996. The 4-week-old compost was applied to mulching depths of 3.8 (68 t dry weight .ha^?1), 7.5 (135 t dry weight .ha^?1), 11.3 (203 t dry weight .ha^?1), and 15 cm (270 t dry weight .ha^?1) in the fall, and at 2.0 (35 t dry weight .ha^?1), 3.8, 7.5, and 11.3 cm depths in the spring. Other treatments were paraquat applied at 0.6 kg.ha^?1 and an untreated control. All treatments were applied in row-alleys between raised, polyethylene-covered soil beds. The 8-week-old compost was applied to depths of 3.8, 7.5, 11.3, and 15 cm in fall and to depths of 2.0, 3.8, 7.5 and 11.3 cm in the spring. Untreated alleys served as controls. In the fall 1995 experiment under low weed pressures, the 4-week-old compost applied to 7.5 cm or greater depths completely inhibited weed germination and growth for 240 days after treatment. In the spring 1996 experiment, 4-week-old compost completely inhibited weed germination and growth for only 65 days if applied to a depth of 7.5 cm or deeper due to higher prevailing weed pressures, particularly due to yellow nutsedge (Cyperus esculentus L.). In the same spring experiment, a 50 % reduction in percentage weed cover was obtained for 240 days with a 11.25 cm deep layer of mulch compared to the control. In the fall 1995 experiment, 8-week-old compost applied at 7.5 cm or depths completely inhibited weed germination and growth for 240 days. In the spring 1996 experiment, 8-week-old compost applied as a 11.25 cm mulch reduced percent weed cover as compared to the control up to 240 days. In general, weed cover and weed dry weight decreased linearly as the depth of the mulch increased.Under these immature composts, inhibition of germination or subsequent weed growth may have been due to both the physical effects of the mulch and the concentrations of phytotoxic fatty acids during the first few days after mulches were applied. At the time of mulching with the 4-week old compost, acetic acid was present at a concentration of 1221 mg.kg^?1 in the fall mulch, and at 4128 mg.kg^?1 in the spring mulch. The same concentrations in the 8-week-old compost for the fall and spring mulches were 1118 mg.kg^?1 and 3113 mg.kg^?1, respectively. In conclusion, immature compost may provide an effective alternative weed control method for row-alleys in vegetable crop production systems. During these experiments, it was observed that man-made contaminants such as glass, hard and soft plastics in the composts were esthetically unacceptable and potentially posed hazards to field workers.     

Upper Profile Changes Over Time in an Appalachian Hayfield Soil Amended with Coal Combustion By‐products

Abstract

Large amounts of flue gas desulfurization (FGD) and fluidized bed combustion (FBC) by‐products from burning coal, consisting primarily of gypsum, are available for potential use as a soil amendment. However, information is limited on longer‐term changes in chemical and physical properties induced over time and over small depth increments of the upper soil profile after applying these amendments. This study examined longer‐term effects in an abandoned Appalachian pasture soil amended with various liming materials and coal combustion by‐products (CCBPs). Soil chemical and physical properties were investigated over time and depths. The results indicated limited dissolution and movement of the calcium (Ca) and magnesium (Mg) applied with the chemical amendments, except for Ca and Mg associated with sulfate. However, sufficient dissolution occurred to cause significant increases in exchangeable Ca and Mg and decreases in exchangeable Al that were reflected in corresponding increases in soil pH. These beneficial effects persisted over time and were confined to the upper 0‐ to 15‐cm depth of the profile. The greatest benefits appeared to be in the upper 0‐ to 5‐cm surface layer. Both Ca and Mg applied as calcitic dolomitic limestone tended to be immobilized in the upper 0‐ to 5‐cm layer of the soil profile; Ca more so than Mg. The presence of S applied in the FGD and FBC amendments appeared to enhance the mobility of Ca and Mg. The ratio of Ca/Mg in HCI extracts from the calcitic dolomitic treatment was close to that of applied calcitic dolomite, implying that the inactive component in soil might be the original calcitic dolomite particles. Soil physical properties measured over small depth increments showed that application of the amendments improved the saturated hydraulic conductivity only in the upper 0‐ to 5‐cm depth and had little or no significant effect on the dry bulk density and plant‐available water.     

启动磷肥不同施用方式对玉米养分吸收及生长和产量的影响

为了探索启动磷肥不同施用方式对玉米生长和产量的影响,设置启动磷肥大田滴施(T1)、穴施(T2)和不施启动磷肥(CK)3个施肥处理,其中启动肥磷肥用量为P₂O₅ 30 kg·hm^-2,探究启动磷肥不同施用方式对玉米生长、养分分配和产量构成的影响;设置启动磷肥根箱土壤滴施(P1)、穴施(P2)和不施启动肥(CF)3个处理,其中启动肥磷肥用量为P₂O₅ 0.2 g·kg^-1土,探究启动磷肥施用后土壤中磷素的空间分布与迁移效果。结果表明,玉米四叶期和六叶期,T1和T2处理均显著增加了苗期玉米总根长,根表面积,地上、地下部生物量和N、P、K养分积累量。在六叶期,T1和T2处理玉米总根长较CK分别增加了21.10%和30.35%,根系表面积分别增加了23.48%和29.20%,地上和地下部生物量分别增加了31.24%和52.38%、33.61%和57.81%。与CK相比,T1和T2处理促进了玉米N、P、K养分的积累,同时促进了养分由营养器官向生殖器官的转移。在玉米吐丝期至成熟期,T1和T2处理玉米N、P、K养分转移量较CK分别增加了29.75和44.73 kg·hm^-2、10.76和14.65 kg·hm^-2、2.20和24.67 kg·hm^-2。玉米穗长、行粒数、产量和磷肥偏生产力均表现为T2>T1>CK,玉米穗秃尖长度表现为T2相似文献   

Nitrogen efficiency of grain sorghum grown on flat and raised seedbeds on poorly drained soil

Grain sorghum (Sorghum bicolor L. Moench) production commonly occurs on poorly drained clayey soils of the Mississippi River delta region inArkansas. Raised, wide seedbeds may improve grain yield and fertilizer N efficiency for narrow‐row sorghum production on these soils. The influence of individual row positions on raised, wide seedbeds was compared to conventional flat seedbed for grain yield, yield components, dry weight, and N uptake. A 193‐cm wide and 15 cm high crowned seedbed (CB) was compared to the flat seedbed (FB) in 1987 and 1988 on a Sharkey silty clay (very fine, mont‐morillonitic, nonacid, thermic, Vertic Haplaquepts) at Keiser, AR. Three rows were planted on each seedbed treatment; one in the middle of the bed and one row 48 cm to each side of the row in the middle. Nitrogen rates of 0, 56, 112, and 168 kg/ha were applied at planting. In addition, two split applications at the 168 kg/ha N rate (56 kg N/ha at planting and 112 kg N/ha at either four‐leaf or eight‐leaf growth stage) were evaluated. Each row position was evaluated for grain yield, yield components, plant dry weight, and N uptake. Whole plant samples were collected at the anthesis and physiological maturity growth stages. The field average grain yield was higher on the CB each year regardless of N rate applied at planting. This yield increase on the CB was related to the row on the top of the CB yielding more than the equivalent row on the FB. The responses of plant dry weight at each growth stage, N uptake at each growth stage, and N content of the seed was similar to grain yield responses. The split N application at planting and the eight‐leaf growth stage was as effective or better than any other treatment for increasing grain yield, N uptake, and seed N content.     

Effect of starter fertilizer in seed-row on emergence,biomass and nutrient uptake by six pulse crops grown under controlled environment conditions

Abstract

Legumes have a unique ability to obtain a significant portion of atmospheric nitrogen (N₂) through a symbiotic relationship with Rhizobia spp of bacteria but it takes time, thus, an early supply of N to the plant may positively influence growth and development. However, too much fertilizer in close proximity to the seed can damage the seedling. Therefore, this study was conducted to determine the maximum safe rates for starter seed-row fertilizer application under low seedbed utilization conditions (15%). Emergence, biomass yield and nitrogen (N), phosphorus (P) and sulfur (S) uptake responses to starter fertilizer products and blends applied at 0, 10, 20 and 30?kg?N?ha^?1 in the seed-row were investigated for six different pulse crops: soybean, pea, faba bean, black bean, lentil and chickpea. The general sensitivity (injury potential) for starter N, P, S fertilizer was lentil?≥?pea?≥?chickpea?>?soybean?≥?black bean?>?faba bean. Lentil, pea and chickpea could generally only tolerate the 10?kg?N?ha^?1 rates while soybean and black bean could tolerate 10–20?kg?N?ha^?1. Faba bean emergence appeared relatively unaffected by all three rates of N and showed least sensitivity to seed row placed fertilizer. In terms of 30-day biomass response, soybean and black bean were most responsive to fertilization, while pea, faba bean, lentil and chickpea were least responsive to the starter fertilizer applications, with no benefit increasing above the 10?kg?N?ha^?1 rate.