Sorghum Residues Research Articles

Nitrogen Nutrition of Rainfed Winter Wheat in Tilled and No‐Till Sorghum and Wheat Residues

AbstractDecomposition of sorghum [Sorghum bicolor (L.) Moench] and wheat (Triticum aestivum L.) plant residues can immobilize enough surface‐applied N to cause a deficiency in successive winter wheat crops. This experiment examined the effects of conventional and no‐till grain sorghum and wheat residues on N requirements of dryland winter wheat. Field experiments conducted from 1987–1991 on an Austin silty clay (fine‐silty, carbonatic, thermic Udorthentic Haplustoll) soil included sorghum and wheat residue treatments with conventional till (CT), no‐till (NT), and residue removal (RR). All residue plots received four preplant N rates (0, 45, 90, and 135 kg N ha−1), with subplots planted to three winter wheat cultivars in 1988 and 1989, and two cultivars in 1990 and 1991. Grain and stover yields were significantly lower when wheat followed sorghum than under continuous wheat. Wheat grain yields at N application rates < 90 kg ha−1 were 39% lower in NT plots vs. CT plots, 5% lower in CT plots compared with yields in RR plots, and 39% lower in sorghum‐wheat rotation compared with continuous wheat. Wheat N uptake at N application rates <90 kg ha−1 was 41% lower in NT plots vs. N uptake in CT plots, 10% lower in CT plots vs. N uptake in RR plots, and 36% lower in sorghum‐wheat rotation vs. continuous wheat. Grain yield and N uptake of wheat at the 135 kg N ha−1 rate were not significantly different in NT and CT plots. Preplant soil NO3‐N analysis indicated a need for the application of N fertilizer at planting in CT and NT sorghum residues, and basal stem NO3‐N analysis showed wheat growing in NT residues and sorghum‐wheat rotations; had higher N fertilizer requirements than continuous CT wheat. Microbial immobilization of surface‐applied N was responsible for N deficiencies observed in NT winter wheat, while a decrease in fallow time between sorghum harvest and wheat planting dates was the primary cause for reduced mineralization rates of residue‐derived and indigenous soil N in sorghum‐wheat rotations. A fallow period following grain sorghum and/or band application of fertilizer N could alleviate N deficiencies observed in this study.

EFFECT OF GRAIN SORGHUM ON GERMINATION OF WEED AND CROP SEEDS

Sorghum species are frequently used by horticultural producers as cover crops or green manures. Grain sorghum cover crops are often used in the southern United States. These summer annual grasses grow rapidly producing large quantities of biomass that has been shown to suppress weeds. Although allelochemicals in the roots and shoots have been identified, the precise mode of weed suppression has not been clearly elucidated. We performed a series of studies to evaluate the effect of sorghum on the germination of various weed and crop seeds. Petri dish assays were used to test the effect of germinating sorghum seed on the indicator species. Treatments were arranged in a completely randomized design with 4 replications and 2 experimental runs. Data collected included % germination as well as radicle and hypocotyl length. A modified Parker bioassay using 4 and 8 week old sorghum root and shoot tissue was used to study the effects of sorghum tissue on seed germination of the indicator species. Sorghum residue was observed to inhibit weed and crop seedling growth resulting in chlorosis of susceptible species.

Residue Placement and Fungicide Effects on Fungal Communities in Conventional and No-Tillage Soils

Residue Placement and Fungicide Effects on Fungal Communities in Conventional and No-Tillage Soils

Decomposition of sorghum residue in a double-crop sorghum and wheat system

An understanding of crop residue decomposition patterns is fundamental to the efficient management of residue, particularly in double-cropping systems. In a 3-yr study conducted at Plains, Ga, decomposition of residue from three grain sorghum [ Sorghum bicolor (L.) Moench] cultivars buried in mesh (53-μm) bags at two different times was monitored for 160–225 d, depending on the year. No consistent differences in decomposition patterns among the cultivars were apparent. Residue dry matter and N loss from both Burial 1 (immediately after sorghum grain harvest) and Burial 2 [prior to planting wheat ( Triticum aestivum L. em Thell), about 50 d after Burial 1] followed exponential patterns. During the interval between Burial 1 and Burial 2, slower decomposition of the standing residue resulted in Burial 2 residue being reduced to means of 77 and 84% of the original dry matter and N values, respectively; whereas, mean values for the buried Burial 1 residue had declined to 50 and 76% for original dry matter and N, respectively. However, by 225 d after Burial 1, both residues had very similar relative dry matter and N values. At 225 d, the mean relative dry matter remaining for Burial 1 and Burial 2 residues were 36 and 33%, respectively. The mean relative N remaining at 225 d for Burial 1 and Burial 2 residues were 67 and 64%, respectively. The C-to-N ratio of the residue decreased linearly with time from an initial mean of 33.3 to a mean of 15.8 after 225 d of decomposition. The results demonstrate that sorghum residue is readily decomposed in soils of the southeastern U.S.A.

Effect of sorghum residues on wheat productivity in semi-arid Argentina. I. Stover decomposition and N distribution in the crop

Humification and residual effects of 3-month-fallowed sorghum residues on the productivity of winter wheat in a petrocalcic Haplustoll soil in semi-arid Argentina were studied. 15N-labelled urea was applied at sorghum harvesting-mulching (or beginning of fallow, F), wheat seeding (S) and tillering (T). Sorghum residues interacted strongly with N added to the soil. Total aerial plant dry matter (tadm) was lowest (4.94 Mg ha −1) when N was added at the beginning of fallow thus indicating a strong N immobilization, and highest (8.30 Mg ha −1) when N was incorporated at S. The N uptake followed a similar pattern. The percentage of N derived from fertilizer and that of recovery as well as the N content of the tadm increased from F to S to T. These data suggest that the sorghum residues immobilize larger amounts of N when it is applied at the beginning of fallowing than when it is incorporated at a later time such as seeding and tillering.

Fallow management, soil water, plant-available soil nitrogen and grain sorghum production in south west Queensland

The effects of tillage frequency (conventional, reduced and zero), primary tillage implement (disc, blade and chisel plough), stubble management (retention and removal), gypsum application, and paraplowing were examined with respect to soil water storage, soil nitrate accumulation, crop establishment, crop growth, grain yield and grain nitrogen content for 4 successive sorghum crops on a sodic, texture-contrast soil in south west Queensland. Retention of sorghum stubble (v. removal) produced an increase in mean yield of sorghum grain of 393 kg/ha, due to increased soil water extraction and increased water use efficiency by the following crop. The highest mean yield occurred after reduced blade tillage with stubble retained. Zero tillage with stubble removed gave the lowest mean grain yield. Zero tillage always had the lowest quantity of soil nitrate-nitrogen at sowing. In one fallow, increased aggressiveness of primary tillage (disc v. blade plough) increased the quantity of nitrate-nitrogen in the top 60 cm of soil at sowing. These effects on available soil nitrogen did not result in corresponding differences in grain nitrogen content. Results indicate that for optimum fallow management on this texture-contrast soil in south west Queensland, sorghum residues should be retained, tillage frequency should be reduced, but not to zero, blade ploughing should be preferred to discing, and gypsum application should not be practised.

Field Crop Recovery and Modeling of Nitrogen Mineralized from Labeled Sorghum Residues

AbstractEfficient use of fertilizer N requires an assessment of the N contribution from decomposing crop residues. The objectives of this study were to quantify and model the amount of mineralized N recovered by a growing crop from 15N‐labeled sorghum (Sorghum bicolor [L.] Moench) residues of variable N concentration and composition. The residues were incorporated into the surface soil of field microplots. The microplots were double‐cropped with sorghum and wheat (Triticum aestivum L.) for a 3‐yr period. The 15N tag in the crop residue was used to distinguish between residue‐derived N and that from soil organic matter. Between 4.5 and 25% of the residue N applied (36–83 kg N ha−1 was applied as crop residue N) was recovered by a sorghum crop 110 d after incorporation. This constituted 56 to 77% of the total N recovered during a 3‐yr period. Accumulated N recovered over time was described by modified first‐order models. Regression analysis indicated that 93% of the variability in N recovered by 110 d could be explained using the C/N ratio and acid‐detergent fiber contents of the residues. Measurements of N mineralized, using the method described above, were compared with predicted N mineralized, using MINIMO (a subroutine of the CERES‐Maize model). After adjusting MINIMO parameters using data collected 110 d after residue incorporation, the slope and intercept of a linear fit between measured and MINIMO‐predicted N mineralized 1097 d after residue incorporation were not different from one and zero, respectively.

Effect of dietary inclusion of refermented sorghum residues on broiler chicken performance

(1991). Effect of dietary inclusion of refermented sorghum residues on broiler chicken performance. Archiv fur Tierernaehrung: Vol. 41, No. 2, pp. 189-194.

Grain and Forage Yield and Stover Quality of Sorghum and Millet in Low Rainfall Environments

SUMMARYThe potential for using sorghum and millet crop residues as fodder was studied in southeastern Botswana. This region is characterized by low, unevenly distributed rainfall and shallow sandy soils. There were significant differences among cultivars for grain and stover yield, digestibility, crude protein, and mineral content, but no species advantage. Stover from all entries was adequate for cattle maintenance inin vitrodry matter digestibility (IVDMD) and most of the minerals tested, but crude protein and phosphorus levels did not always meet the minimum requirement. The deficient phosphorus levels were compounded by high calcium levels. This mineral imbalance could lead to bone abnormalities and reduced fertility in livestock.

Influence of sorghum residues and tillage on soil organic matter and soil microbial biomass in an australian vertisol

Short- and medium-term changes in soil organic matter content following a change in soil management or land use are often difficult to measure because they occur slowly against a large background of soil organic matter which can have considerable spatial variability. Results from an experiment with grain sorghum ( Sorghum bicolor L.) on a vertisol in sub-tropical Australia demonstrate the usefulness of two techniques for detecting trends in surface soil organic matter before they can be assessed by conventional methods. Firstly, using soil microbial biomass C as a sensitive indicator of changes in soil organic matter. Secondly, by using initial values of soil organic C or total N, measured before imposition of treatments, as a covariate in an analysis of variance. The combination of these techniques provided the most sensitive approach for detecting changes. The above-ground residues of sorghum (41 dry matter ha −1) were either retained or removed from plots that received conventional or zero tillage for 6 yr. Averaged over tillage treatments, soil organic C in the surface 0–10 cm layer was 8% greater in the residue-retained than in the residue-removed treatment, a difference equivalent to 16% of the C added as residues. The trend to increased soil total N was not significant. Residue retention caused larger percentage increases in microbial biomass C, measured by the chloroform fumigation-incubation method, than in total organic C and total N. The increase in biomass C was 12%, biomass N 23% and biomass P 45%, equivalent to 0.7% of the C, 7% of the N and 32% of the P added in residues. Residue retention decreased the biomass C-to-P ratio from 48 to 35, but these values were still much wider than those previously measured in U.K. soils. Residue retention increased respiration by about 45% (measured by CO 2 evolution during a 30-day incubation) but had little effect on biomass C-to-N ratio or mineralization of N. Averaged over the two residue management treatments, soil organic C in the surface 10 cm layer was 7% greater under zero tillage than under conventional tillage. The corresponding increase in biomass C was 14–21%, but there were no differences in biomass N or biomass P. CO 2 evolution and specific respiration by the biomass (μ g CO 2-C evolved g −1 biomass C day −1) were less in zero-tilled than in conventionally tilled soils. The combined effects of residue retention and zero tillage caused increases of 15% in surface soil organic C, 18% in soil total N and 31% in biomass C.

Effect of tillage and furrow irrigation timing on efficiency of preplant irrigation

A field study to determine the efficiency of preplant irrigating with furrow irrigation and the effects of tillage and fall or spring application of preplant irrigation on this efficiency was conducted during 1983, 1984, and 1985 at the Texas Agricultural Experiment Station, North Plains Research Field at Etter, Texas on a Sherm, silty clay loam soil. Sorghum residue from the previous crop was shredded, gravimetric soil samples were taken, and five tillage treatments were imposed in the fall. The tillage treatments consisted of various combinations of disking, chiselling, moldboard plowing, and disk bedding. A preplant irrigation was applied in the fall to half of each tillage plot and in the spring to the other half of each plot. Soil samples were taken from each plot one month after the spring preplant irrigation. Sorghum (Sorghum bicolor L. cv. ‘NC 178’) was planted and irrigated similarly on all plots during the growing season. On the average, 237 mm of water were required to irrigate the tillage treatments during fall preplant irrigation and 466 mm were required during spring preplant irrigation. The additional water requirement in the spring was associated with increased water uptake by non-wheel-track furrows. Treatments with chiselling required larger water application during spring preplant irrigation. All treatments had similar soil water contents at planting time. Neither timing of preplant irrigation nor type of tillage had any effect on sorghum grain yield. Therefore, fall preplant irrigation was considerably more efficient than spring preplant irrigation. Averaged over the three years do study and five tillage treatments storage efficiency was 26% for fall application and 17% for springtime.

Effect of pH on nitrogen mineralization in crop-residue-treated soils

This study compares N mineralization in soils treated with crop residues [corn (Zea mays L.), soybean (Glycine max (L.) Merr.), sorghum (Sorghum vulgare Pers.)] or alfalfa (Medicago sativa L.) at three adjusted soil pH values (4, 6, and 8); pH was adjusted with dilute H2SO4 or KOH. A sample of soil (20 g) was treated with 0.448 g plant material (equivalent to 50t ha−1), mixed with 20 g silica sand adjusted to the pH of the soil, and packed in a leaching tube. The soil-sand mixture was leached with 100 ml 5 mM CaCl2 adjusted to the same pH as that of the treated soil to remove the initial mineral N, and incubated at 30°C. The leaching procedure was repeated every 2 weeks for 20 weeks. Results from three soils showed that N mineralization increased as the soil pH increased. In one soil (Lester soil), significant amounts of NH 4 + -N accumulated at pH 4 during the first 12 weeks. Treatment with corn and soybean residues resulted in a marked reduction in N mineralization, especially at pH 4. The percentage of organic N mineralized from sorghum residue and alfalfa added to soils increased as the soil pH increased; the values ranged from 7.7% to 37.0% for sorghum and from 17.2% to 30.1% for alfalfa.

Laboratory experiments on the effects of antecedent moisture content and residue application on structural properties of a fragile soil

In model experiments, saturated hydraulic conductivity ( K s) of a fragile Miles fine sandy loam soil dried at 35°C was increased by incorporating sorghum residue, but decreased by increasing antecedent moisture. After 4 drying cycles at 35°C, the K s of soil with no residue ranged from 0.002 cm h −1 when antecedent moisture was high to 1.4 cm h −1 when antecedent moisture was very low. The K s of soil with high residue ranged from 0.4 cm h −1 when antecedent moisture was high to 11.2 cm h −1 when antecedent moisture was low. The K s of slow-dried soil at 25°C, unlike fast dried soil, increased with increasing moisture. Slow-drying at 25°C or under a straw much increased natural compaction and reduced K s of soils. Finally, the K s of soils was a function of drying conditions, straw management, antecedent moisture and their interactions. These results indicate that slow-drying and increased moisture created by conservation or reduced-tillage systems can increase natural compaction and decrease permeability of some soils.

Mineralization of Nitrogen from Nitrogen‐15 Labeled Crop Residues Under Field Conditions

AbstractThe management of crop residues and their contribution to the supply of plant nutrients is intimately tied with N cycling in the soil. Any attempt to utilize crop residues to the fullest extent requires an understanding of how the system functions. The objective of this research was to determine the extent and rate of N mineralization from 15N‐labeled winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] residues. In addition, the influence of soil texture and fertilizer N on net N mineralization also was evaluated. Nitrogen mineralization from decomposing crop residues was followed by means of plant and soil sampling during subsequent cropping seasons. Plant N uptake and soil inorganic N data showed that 12 to 15% of wheat residue N and 12 to 33% of sorghum residue N were mineralized after one cropping season. Net mineralization differences between crop residues may be attributed to both the C/N ratios and chemical composition of these plant materials. Soil texture and the addition of fertilizer N mainly influenced the initial rate of mineralization, particularly with the wheat residue. There was also evidence of N immobilization of the recently mineralized 15N followed by remineralization later in the growing season for wheat and sorghum residues decomposing in the medium‐textured soils. This immobilization occurred during a period of rapidly increasing soil temperatures. On avg, 79% of the mineralized wheat residue N and 82% of the mineralized sorghum residue N were utilized by wheat and sorghum plants, respectively. Based on these results, the greatest proportion of N mineralized from decomposing wheat and sorghum residues appears to coincide with plant N demand by the subsequent crop, irrespective of differences between C/N ratios of these residues or soil texture.

Effects of N Fertilization on Yield, Growth, and Extraction of Water by Wheat Following Soybeans and Grain Sorghum1

AbstractNitrogen fertilization is an important part of wheat (Triticum aestivum L.) production. It is especially important in double‐crop wheat production because the N system is influenced by previous crop residue. Our objective was to evaluate topdressed rates of 0, 34, 68, 102, and 136 kg N ha−1 as ammonium nitrate spring‐applied to soft red winter wheat (‘Arthur’) grown in double‐cropping sequence following soybeans [Glycine max (L.) Merr] or grain sorghum [Sorghum bicolor (L.) Moench]. The soil was Okolona silty clay (a fine montmorillonitic, thermic Typic Chromudert). We also evaluated a 34 kg ha−1 rate of fall‐applied N with topdressed rates in the spring bringing total N to the same levels as the single spring‐applied topdressed rates above. The effects of previous crop on grain yield, straw yield, plant height, and N uptake were pronounced. All of these were significantly higher following soybeans. We attributed this to greater availability of N following soybeans, but have not ruled out the possibility of a phytotoxic effect associated with grain sorghum residues. There was yellowing and stunting of early wheat growth following grain sorghum across all N rates, regardless of whether fall N was applied or not. This early depression may have led to yield differences that were not completely overcome by the conditions of this study. Depletion of soil water was related to N uptake and yield. Soil moisture from anthesis throughout grain filling decreased progressively faster under wheat that received high rates of N.

Use of phytotoxic plant residues for selective weed control

Both fall- and spring-planted grasses were evaluated for weed-suppressing ability after desiccation by freezing, glyphosate or paraquat. Populations of Portulaca oleracea L. and Digitaria ischaemum (Schreb.) Muhl. were reduced by 70% and 98%, respectively, by residues of sorghum ( Sorghum bicolor L.). Total weed biomass and weight of several indicator species were also consistently reduced with residues of barley ( Hordeum vulgare L.), oats ( Avena sativa L.), wheat ( Triticum aestivum L.) and rye ( Secale cereale L.), as well as the sorghums. In general, the larger-seeded vegetables, particularly legumes, grew normally or were sometimes stimulated by the cover-crop residues, whereas several species of smaller-seeded vegetables were severely injured. The use of Populus wood shavings as a control mulch allowed separation of physical and chemical aspects of the residues. Glasshouse experiments with two soils confirmed both weed-suppressing and crop-stimulating effects of sorghum residues. Water extracts of sorghum herbage were toxic to indicator species in sterile bioassays: this suggests that phytotoxins are directly released by the plant residues.

Response of Crops to Sorghum Residues1

Abstract Vegetable and field crops were grown on young residues of several cultivars of sorghum (Sorghum vulgare Pers.) in the greenhouse and field. Seedling growth of field corn (Zea mays L.) in the greenhouse was increased by residues of sorghum shoots, but not by residues of sorghum roots. In contrast the growth of sweet corn in the field was always decreased by residues of ‘Bird-a-Boo’ sorghum roots and whole plants. The growth and yield of snap beans (Phaseolus vulgaris L.) in the field was increased or decreased by sorghum residues depending on the sorghum plant part, quantity, cultivar, and soil environment. Although sorghum residues may stimulate crop growth in some instances, this stimulation was not easily controlled because the optimal range of sorghum residues and soil environment is too narrow and unpredictable.

Effects of crop residues, soil type and temperature on emergence and early growth of wheat

Two controlled environment experiments were conducted to examine the germination and early growth of wheat (Triticum aestivum L. cv. Songlen) growing under crop residues of rape, sorghum, field pea and wheat. Additional treamments also included were soil type (Lithic Vertic Ustochrept and Plinthustalf) and temperature (8°C and 24°C to simulate winter and autumn sowing conditions). At low temperature, wheat and sorghum residues produced the most adverse effects on germination with all residues reducing emergence at high temperatures. Shoot lengths were also reduced by most residues at high temperatures whilst root lengths and shoot and root dry weights were unaffected by residue treatments. These results suggest major phytotoxic effects of residues during early growth (up to 14 days after sowing) with, in general, few interactions with soil type or temperature.

Quantification of Allelopathic Potential of Sorghum Residues by Novel Indexing of Richards' Function Fitted to Cumulative Cress Seed Germination Curves

The inhibitory activity of aqueous extracts of field-grown sorghum (Sorghum bicolor cv. Bird-a-boo) herbage and roots was quantitatively indexed by three aspects of cumulative cress (Lepidium sativum cv. Curlycress) seed germination: the germination onset; weighted mean rate; and final germination percentage. Extract potency was greatest for herbage collected four weeks after planting but declined sharply thereafter as the plants matured. About 91% of the inhibitory activity obtained from four-week-old herbage was in a low molecular weight fraction. Differential effects of herbage and root extracts on cress seed germination suggest that the nature and/or proportion of biologically active substances extractable from these plant parts is dissimilar.

Economic implications of cotton gin trash and sorghum residues as alternative energy sources

This paper analyzes the economic implications of energy production from cotton gin trash and sorghum residues. Using cotton gin trash, on-farm cost of gasification ranged from $7.83 to $3.56 per million Btu, electricity generation, operating year around was about 6.15 cents per kWh. Cost of producing gas, using gin trash or grain sorghum residue, in a farmer cooperative was over $3.75 per million Btu. These costs are not economically attractive at this time. Using gin trash at the gin site, the cost of electricity generation was 5.3 cents per kWh and gas production was $2.75 per million Btu. About 70% of the electricity produced, however, must be sold for approximately 2 cents per kWh resulting in over $250,000 of costs not covered. Although gas production at the gin site is very competitive with the current market price of natural gas, the low Btu gas is not a comparable fuel. The cost of producing pellets from gin trash for energy ranged from $2.20 to $3.89 per million Btu. Gin trash pellets are not competitive with natural gas, but they are a potentially attractive alternative to diesel or fuel oil as a stationary engine fuel source.