Greater Dry Matter Yield Research Articles

Nitrogen-Rich Sewage Sludge Mineralized Quickly, Improving Lettuce Nutrition and Yield, with Reduced Risk of Heavy Metal Contamination of Soil and Plant Tissues

Sewage sludge should primarily find use in agriculture, reducing the quantity directed towards alternative disposal methods like incineration or deposition in municipal landfills. This study evaluated the agronomic value and the risk of soil and plant tissue contamination with heavy metals in sewage sludge obtained from two wastewater treatment plants (WWTP). The experiment was arranged as a 2 × 5 factorial (two sewage sludges, five sanitation treatments), involving lettuce cultivation in pots over two growing cycles. The two sewage sludges were sourced from the WWTPs of Gelfa and Viana do Castelo and underwent five sanitation and stabilization treatments (40% and 20% calcium oxide, 40% and 20% calcium hydroxide, and untreated sewage sludge). The Gelfa sewage sludge, characterized by a higher initial nitrogen (N) concentration, resulted in greater dry-matter yield (DMY) (12.4 and 8.6 g plant−1 for the first and second growing cycles, respectively) compared to that from Viana do Castelo (11.0 and 8.1 g plant−1), with N release likely being a major factor influencing crop productivity. The high N concentration and the low carbon (C)/N ratio of sewage sludge led to rapid mineralization of the organic substrate, which additionally led to a higher release of other important nutrients, such as phosphorus (P) and boron (B), making them available for plant uptake. Alkalizing treatments further stimulated sewage sludge mineralization, increasing soil pH and exchangeable calcium (Ca), thereby enhancing Ca availability for plants, and indicating a preference for use in acidic soils. Cationic micronutrients were minimally affected by the sewage sludge and their treatments. The concentrations of heavy metals in the sewage sludge, soils, and lettuce tissues were all below internationally established threshold limits. This study highlighted the high fertilizing value of these sewage sludges, supplying N, P, and B to plants, while demonstrating a low risk of environmental contamination with heavy metals. Nevertheless, the safe use of sewage sludge by farmers depends on monitoring other risks, such as toxic organic compounds, which were not evaluated in this study.

KAYSERİ EKOLOJİK KOŞULLARINDA MACAR FİĞİ (Vicia pannonica Crantz.) + ARPA (Hordeum vulgare L.) KARIŞIK EKİM SİSTEMİNDE UYGUN KARIŞIM ORANLARININ BELİRLENMESİ

Bu çalışma; Kayseri ekolojik koşullarında macar fiği + arpa karışık ekim sisteminde uygun karışım oranlarını belirlemek amacı ile, 2015-2017 yıllarında Beta macar fiği ve Bülbül-98 arpa çeşidi kullanılarak tesadüf blokları deneme desenine göre 4 tekerrürlü olarak yürütülmüştür. Denemede, saf ekimler ile birlikte % 70 arpa + % 30 macar fiği, % 50 arpa + % 50 macar fiği ve % 30 arpa + % 70 macar fiği karışımları yer almıştır. Araştırmada kuru madde verimi, kuru otta macar fiğ oranı, ham protein oranı ve verimi, asit deterjan lif (ADF) ve nötr deterjan lif (NDF) oranları ile nispi yem değeri (NYD) incelenmiştir.
 
 Çalışmada, elde edilen sonuçlara göre; karışımda macar fiğ oranı arttıkça kuru madde veriminin azaldığı ve en yüksek kuru madde veriminin arpa yalın ekiminden elde edildiği tespit edilmiştir. Ancak karışımda macar fiğ oranı arttıkça NDF oranı azalmış, protein oranını ise artmıştır. İki yıla ait verim ve kalite (ADF, NDF, NYD ve protein) parametreleri birlikte incelendiğinde %70 macar fiği+%30 arpa karışımları Kayseri ve benzer ekolojiler için önerilebilir.

Nitrogen levels and age at harvest and their effects on the nutritive value and fermentative characteristics of corn (Zea mays L.)

The experiment consisted of two dates of planting [in September (D1) and February (D2)] of maize (Zea mays L.) DKC 67-60, to evaluate the effect of four N fertilization levels (0, 56, 112 and 185 kg/ha) and three ages at harvest [70, 77 and 84 days after planting (DAP)] on dry matter yield (DMY) of the leaves, stem, ear and of the entire plant; and as indicators of nutritive value [crude protein (CP) and neutral detergent fiber (NDF)] of harvested material prior to ensiling. In both plantings, the levels of N affected (P<0.05) DMY of leaves, stems, ears and entire plant, exhibiting both a linear and a quadratic response, and suggesting that the optimum N application rate is between 112 and 185 kg/ha. Age at harvest date affected (P<0.05) DMY of stems, ears and entire plant, but not that of the leaves. Greater DMY was observed at 84 DAP for all components. The CP concentration was greater in the forage of the first planting (D1). Increasing N application rates increased CP, but had no effect on NDF concentration. Age at harvest had no effect on CP, but progressively increased NDF. Both pH and organic acid concentrations in the silages were similar with the four N levels; all of the silages showed good fermentation characteristics.

Introduction of four native legumes of the Canadian Prairies in monoculture and in mixtures with meadow bromegrass (Bromus riparius)

Many questions remain concerning the viability and productivity of seeding native legumes in the Canadian Prairies for forage production. Field research was conducted with four native legume species (Astragalus flexuosus, Dalea purpurea, Hedysarum boreale, and Vicia americana) to evaluate performance in Swift Current and Saskatoon, SK. The experimental design was a randomized complete block design with four replicates to evaluate legume–grass mixtures and monoculture performance, botanical composition, and effect of harvest dates (July and August) from 2016 to 2018. The native legume–grass mixtures performed differently at the sites, with greater foliar cover at Saskatoon but a greater proportion of legumes in mixtures at Swift Current. The mixtures had similar forage nutritive value as monoculture Bromus riparius, with legumes contributing 10% or less of the forage dry matter yield (DMY) at both sites. Astragalus flexuosus showed the greatest foliar cover and produced the greatest DMY in monoculture at both sites. Based on this study, native legumes would need to make up a larger proportion of forage dry matter yield to change the nutritional value of mixtures. In a subsequent seeding rate evaluation, the four legume species were planted at three seeding rates [300, 200, and 100 pure live seeds (PLS) per metre] and tested for DMY one year following establishment near Swift Current. Increasing seeding rates up to 300 PLS·m−1 corresponded with an increase in seedling density and foliar cover, but DMY was not affected. Additional research with A. flexuosus is needed to demonstrate its value as a forage.

Morphological, productive, and nutritional characterization of Desmanthus spp. accessions under different cutting intensities

Rangeland legume species from the Brazilian Caatinga play a key role as feed resources for livestock and are an alternative in the agroforestry systems. This study evaluated the effect of two cutting intensities (40 and 80 cm) on morphological, productive, and qualitative characteristics of four (5G, 6G, 7G, and AS) accessions of Desmanthus spp. The experiment was established considering a completely randomized design with subdivided plots and six replicates at the Sugarcane Experimental Station, Carpina/UFRPE. Every 70 days, the variables fruiting, pod production, number of leaves, number of branches, leaves per branch, leaves per plant, and branch diameter were evaluated. The leaf/branch ratio, dry matter yield (DMY), chemical composition, and in vitro dry matter digestibility (IVDMD) were determined. There was no interaction (p ≥ 0.05) between the cutting intensities and evalutaed accessions for the morphological and nutritional variables. The effect of accessions on stem diameter, number of leaves per branch and per plant, leaf/branch ratio, and IVDMD was significant. The AS accession had the greatest values of plant DMY and branch DMY (1.85 and 1.27 ton DM ha−1), respectively, under the harvest intensity of 40 cm. The 7G accession, however, had greatest DMY when harvested at 80 cm, producing 1.52 and 1.00 ton DM ha−1 for total DMY and branch DMY, respectively. The Desmanthus spp. accessions evaluated in this study varied in their morphological, productive, and nutritional characteristics.

Forage yield and morphogenesis of Megathyrsus maximus cultivars in Roraimas’s savannas

In order to evaluate the forage productivity and the morphogenic and structural characteristics of Megathyrsus maximus cultivars (Massai, Mombasa, Kenya, Tamani, Tanzania and Zuri), an experiment was conduct under natural environmental conditions in the savannahs of Roraima. The highest yields of green dry matter (GDM) were found with cultivars Zuri (4,317 kg ha-1) and Mombasa (4,115 kg ha-1), followed by Kenya (3,868 kg ha-1) and Tamani (3,755 kg ha-1), while Massai (3,341 kg ha-1) and Tanzania (3,225 kg ha-1) were the least productive. GDM yield was directly correlated with LAI and inversely proportional to tiller population density (TPD). The cultivars Tanzania and Kenya had the highest number of tiller leaves and leaf appearance rates, while the highest leaf expansion rates were estimate in cultivars Zuri and Kenya. The highest average length of tiller leaves was estimate in the cultivars Zuri and Mombasa. Leaf senescence rates were inversely proportional to TPD and the highest recorded with the cultivars Mombasa and Tamani. The six cultivars of M. maximus showed satisfactory forage yields and can be recommend for cultivation in the edaphoclimatic conditions of the of Roraima’s savannas. The determination of morphogenic and structural characteristics can contribute to the establishment of appropriate and specific management practices for each cultivar, aiming to optimize its productivity and reduce losses due to leaf senescence.

Effects of planting population, genotype, and nitrogen fertilization on dry matter yield, nutrient composition, in vitro ruminal neutral detergent fiber disappearance, and nitrogen and phosphorus removal of corn for silage

The objective of this study was to evaluate the effects of corn planting population with different fertilization rates on forage dry matter (DM) yield, silage quality and digestibility, and nutrient removal from the soil in a commercial dairy farm. The study was performed in 2 fields during the springs of 2017 and 2018 at a 425-cow commercial dairy farm located in Crockett, Virginia (USA). Conventional (CONV) and brown midrib (BMR) corn genotypes were planted at a theoretical planting population of 60,000, 75,000, and 90,000 seeds/ha (60 K, 75 K, and 90 K, respectively). Four plots were planted for each planting population and genotype in each field during each year. In addition to pre-planting (200 kg N/ha) and planting (55 kg N/ha) fertilization, plots were fertilized with 50 or 100 kg N/ha when the crop showed 6 visible leaves (V6). Resulting populations were 63,200, 72,600, and 86,300 plants/ha for 60 K, 75 K, and 90 K, respectively. Planting corn at 90 K resulted in the greatest DM yield (21.4 Mg/ha), whereas DM yield was similar for 75 K and 60 K (20.3 Mg/ha). An interaction between planting population and year existed for DM yield. Doubling the dosage of N fertilizer at V6 increased biomass yield only by 3.1 %. Even though the number of kernels per plant increased with double N fertilization, an interaction did not exist between corn planting population and N fertilization. The CONV corn yielded 19.2 % more than the BMR corn (22.5 vs. 18.9 Mg/ha, respectively). Planting population affected the concentrations of crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and phosphorus (P), although the magnitudes of these changes have minor nutritional or productive implications. Also, planting population did not affect the concentrations of ash, starch, and sugars. Planting corn at 60 K resulted in the greatest concentration of P (2,661 mg P/kg DM), whereas the concentration of P was similar for 75 K and 90 K (2,566 and 2,552 mg P/kg, respectively). Neither corn planting population or N fertilization affected in vitro dry matter digestibility (IVDMD) or in vitro neutral detergent fiber digestibility (IVNDFD). In conclusion, increasing corn planting population and N fertilization had minimal or no effects on corn silage composition and digestibility. Future studies should directly evaluate the interaction between corn planting population and crop maturity on DM yield and on nutrient composition and digestibility of corn for silage.

Effects of Nitrogen Fertilization on Forage Production and Nutritive Nalue of Geukdong 6, Teosinte Hybrid 〔<i>Zea mays</i> L. subsp. <i>mexicana</i> (Schrad.) H. H. Iltis〕

This study was conducted to evaluate the effects of different nitrogen levels on the yield and nutrient quality of a newly developed domestic hybrid of Teosinte, Geukdong 6〔Zea mays L. subsp. mexicana (Schrad.) H. H. Iltis〕. The field experiment was conducted in a randomized block design with three replicates and consisted of four nitrogen (N) application rates, T1 (200 kg/ha), T2 (300 kg/ha), T3 (400 kg/ha), and T4 (500 kg/ha). No differences were found in plant length, leaf length, leaf width, leaf number, dead leaves, stem hardness, tiller number, and fresh yield (p>0.05). The T3 showed significantly greater dry matter yield at harvest (heading stage) compared to the other treatments (p 0.05). The sugar content was higher in the T2 treatment than the other treatments (p 0.05). Na content was higher in order of T2 > T4 > T3 > T1 (p 0.05). Given these results, we recommend the amount of nitrogen fertilization necessary for “Geukdong 6” to be around 400 kg per ha (T3), when considering, high fresh yield, dry matter yield, number of leaves and content of crude protein.

Forage yield, chemical composition and morphogenesis of Brachiaria brizantha cv. Piatã under regrowth periods

With the objective to evaluate the effects of regrowth period (14, 21, 28, 35 and 42 days) on green dry matter yield (GDMY), chemical composition and morphogenetic and structural characteristics of Brachiaria brizantha cv. Piatã, was carried out an experiment under greenhouse with natural conditions of light and temperature. GDMY yields and regrowth, leaf blade length, and leaf lifespan rate increased consistently (P<.05) with regrowth period, however the nitrogen, phosphorus, magnesium and potassium contents decreased as regrowth period, while calcium contents were not affected by regrowth period. Maximum GDMY, leaf appearance and elongation rate, and leaf blade length were obtained with regrowth periods at 38.2; 41.1; 31.3 and 38.9 days, respectively. These data suggest that cutting at 35 to 42 regrowth days were optimal for obtain maximum yields and regrowth of rich forage and pasture persistence.

Effects of Different Nitrogen Dose and Sources as Top-Dressing on Yield and Silage Quality Attributes of Silage Maize

Effects of different nitrogen doses and sources applied as top-dressing on dry matter yield and quality of maize silage were investigated in this study. Along with 7.5 kg N da-1 application as starter at sowing in the form of 15-15-0+Zn, nitrogen doses of 0, 7.5, 15 and 22.5 kg da-1 were applied as top-dressing at 6-leaf stage of plants in the forms of ammonium nitrate, urea, DMPP blended ammonium sulphate nitrate and urea with NBPT urease inhibitor. Experiments were conducted in randomized blocks-factorial experimental design with 3 replicates in 2013 and 2014. The greatest dry matter yield were obtained from 15 and 22.5 kg N da-1 in 2013 and from 22.5 kg N da-1 in 2014. Nitrogen sources had also significant effects on dry matter yield. According to the average of two years, both DMPP blended ammonium sulphate nitrate and urea with NBPT urease inhibitor increased yield respectively by 7 and 3% as compared to ammonium nitrate and urea fertilizers. Nitrogen doses significantly improved the silage quality attributes. Nitrogen treatments increased silage protein ratio and decreased ADF and NDF ratios of silage samples. The greatest relative feed value was obtained from 15 kg N da-1 treatment. It was concluded based on present findings that besides the nitrogen doses, nitrogen sources also significantly improved yield.

Forage Yield and Quality Attributes of Berseem Clover Genotypes under Mediterranean Climate

It is quite significant to develop annual and high-yield forage legumes to be pure-sown or intercropped with graminae species in winter cropping systems of Mediterranean region. In this sense, berseem clover is considered as a significant species for Mediterranean region. Therefore, this study was conducted to determine yield and herbage quality attributes of berseem clover (Trifolium alexandrinum L.) genotypes in Çukurova region with dominant Mediterranean climate. Experiments were conducted over the experimental fields of Eastern Mediterranean Agricultural Research Institute (Doğankent/Adana) in winter intermediate cropping system (November-April) of 2010-11 and 2011-12 growing seasons. Experiments were carried out in randomized blocks design with 3 replications. In the first and second year of the experiments, green herbage (GH) yields varied respectively between 53.3-79.7 and between 22.7-32.3 t/ha; dry matter (DM) yields varied respectively between 7.26-12.02 and 5.16-7.42 t/ha; crude protein (CP) ratios varied respectively between 11.37-15.39 and between 15.22-18.88%; digestible dry matter (DDM) ratios varied respectively between 61.10-68.08 and between 56.84-67.70%, acid detergent fiber (ADF) ratios varied respectively between 27.22-41.45 and between 23.07-31.41%; relative feed values (RFV) varied respectively between 99.3-155.0 and between 146.5-190.5. In both years, genotypes 3, 8, 15, 16, 17 and18 had greater DM yields than the standard cultivar and the other genotypes. These genotypes were also prominent w-for herbage quality attributes. Genotype 18 was registered under the name of “DERYA” in 2015 and the other promising genotypes are still being used in on-going breeding studies.

Rendimiento de forraje y sus componentes en variedades de alfalfa en el altiplano de México

La alfalfa (Medicago sativa L.) es la leguminosa cultivada más usada para la producción de leche y carne en México, debido a su alto rendimiento y calidad nutrimental. El objetivo de este estudio fue evaluar el rendimiento de forraje y sus componentes en cinco variedades de alfalfa con intervalos de corte definidos estacionalmente. Las variedades Aragón, Valenciana, Chipilo, Milenia y Oaxaca se distribuyeron aleatoriamente en 20 parcelas experimentales de 12 x 9 m, de acuerdo a un diseño de bloques completos al azar con cuatro repeticiones. Las evaluaciones incluyeron rendimiento de forraje en base seca, peso por tallo, población de tallos m-2, población de plantas m-2, relación hoja:tallo, composición botánica y morfológica. El rendimiento mayor y menor la obtuvieron las variedades Milenia y Aragón con 20,643 y 14,488 kg MS ha-1. El peso por tallo fue mejor en Aragon, Chipilo y Milenia y menor en Valenciana y Oaxaca. Aragón obtuvo la mayor densidad de tallos con 634 tallos m-2 y Oaxaca con 512 tallos m-2 el menor. La relación hoja:tallo mayor la presentó Aragón con 1.31 y la menor Oaxaca con 1.13. En otoño e invierno se obtuvo mayor cantidad de hoja, independientemente de la variedad; y en verano, hubo incremento de maleza en todas las variedades. Existió estacionalidad en el rendimiento; primavera y verano son las épocas con producción mayor, debido a la temperatura y el peso por tallo mayor. La variedad con mayor rendimiento de materia seca fue Milenia y la menor Aragón.

Harvest timing and N application rate effects on switchgrass yield, nutrient cycling, and partitioning

ABSTRACTHarvest time (HT) and nutrient management may have an effect on switchgrass (Panicum virgatum L.) yield and nutrient cycling. Experimental objectives were to quantify HT and nitrogen (N) rate effects on dry matter yield (DMY), nutrient concentration, and N use. “Alamo” switchgrass was grown under four N rates (0, 40, 80, and 120 kg ha−1) with six monthly HT (May to October) in a randomized complete block design experiment with a split-plot arrangement. Yield increased cubically and quadratically with HT in Years 1 and 2. Aftermath yield decreased linearly with HT in both years. N rate increased yield in Year 2 only with no yield benefit at rates >40 kg N ha−1. Nutrient concentration decreased from May to October, while its removal was determined by DMY. N use and recovery were greatest at 40 kg N ha−1 and declined with additional N inputs. Results indicate that harvesting post-frost-kill produced greater DMY with less nutrient concentration and removal.

Agronomic and genetic diversity in intermediate wheatgrass (Thinopyrum intermedium)

AbstractIntermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & D. R. Dewey] plant introductions (PI) have played a critical role in the development of improved intermediate wheatgrass cultivars. The objective of this study was to characterize a large number of intermediate wheatgrass populations over its native range for dry matter yield (DMY), crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fibre (NDF), and rhizome development and genetic diversity and structure to identify superior populations and possible geographical regions in which to collect. Analysis of molecular variance using 643 AFLP bands partitioned 31% of the total genetic variation among these populations with 69% variance detected within populations. Bayesian cluster analysis identified two large groups designated as Asian and European under K = 2. In general, European accessions had greater DMY than did Asian accessions. Observed trends were towards greater CP values in populations with Asian ancestry. Selection index values above zero were observed in populations with European ancestry, and the exception was the late‐maturing (208 days to bloom) populations with Asian ancestry. Plant populations 383 551, 383 561, 401 161, 401 173, 440 021, 578 692 (cv. Tegmar) and 598 740 had rhizome scores greater than 7.0. Despite significant differences detected between populations (ΦST = 0.3136; P < 0.001), there was strong indication of admixed co‐ancestry or possible gene flow between K = 2–9 models.

Agronomic Response of Crops Fertilized with Struvite Derived from Dairy Manure

Three experiments were performed to compare the P availability between struvite and the commercial fertilizer monoammonium phosphate (MAP). Experiment 1 evaluated triticale grown in a commercial potting medium and fertilized with struvite and MAP at 0, 56, 112, and 224 kg P2O5 ha−1. Struvite was comparable for dry matter (DM) yield (P < 0.01) and resulted in greater concentrations of P (P < 0.005) compared to MAP. Experiment 2 evaluated triticale and oats planted in two soils differing in pH, and fertilized with either struvite or MAP at 0, 56, 112, and 224 kg P2O5 ha−1. When oats were grown in acidic soil, struvite provided greater P uptake (P < 0.0001) and concentration of P (P < 0.0001) in the plant compared to MAP. When triticale was grown in acidic soil, struvite provided the greatest DM yield (P < 0.005), P uptake (P < 0.0001), and concentration of P (P < 0.0001) compared to MAP. When triticale and oats were grown in alkaline soil, struvite produced the greatest concentration of P (P < 0.003) compared to MAP for oats. Experiment 3 evaluated corn and alfalfa over a 3-year period planted in alkaline soil and fertilized with either struvite or MAP at 0, 140, and 280 kg P2O5 ha−1. In 2006 and 2007, struvite and MAP were comparable for DM yield (P < 0.05) and concentration of P (P < 0.05) in alfalfa. Using MAP resulted in greater P uptake (P < 0.05) all 3 years for alfalfa, and greater DM yields (P < 0.05) and concentrations of P (P < 0.05) in 2008. For corn, MAP produced the greatest DM yield (P < 0.001), P uptake (P < 0.003), and concentration of P (P < 0.001) all 3 years. Struvite was a comparable or superior P fertilizer compared to MAP in acidic soils and inferior to MAP in alkaline soils.

Eficiência do uso da radiação solar e índices morfofisiológicos em cultivares de feijoeiro

A cultura do feijoeiro apresenta ampla adaptação edafoclimática, o que permite o seu cultivo durante todo o ano. Contudo, para obterem-se bons patamares de rendimento econômico, é fundamental compreender os processos que afetam o crescimento e desenvolvimento da cultura, em diversos ambientes. Este estudo objetivou comparar duas cultivares de feijoeiro (BRS Radiante e Pérola), contrastantes no ciclo e hábito de crescimento, por meio de índices morfofisiológicos e eficiência de uso da radiação solar. Determinaram-se as seguintes características: coeficiente de extinção de luz, eficiência no uso da radiação, desenvolvimento fenológico, índice de área foliar, massa de matéria seca total, taxa de crescimento da cultura, taxa de crescimento relativo e partição da massa de matéria seca. A cultivar BRS Radiante apresenta maior vigor, quando comparada à cultivar Pérola, devido ao desenvolvimento fenológico inicial mais rápido e maiores taxas de crescimento inicial e relativo. As cultivares não diferem quanto ao coeficiente de extinção de luz, embora apresentem diferença quanto ao índice de área foliar e arquitetura da parte aérea. A cultivar BRS Radiante apresenta maior eficiência de uso da radiação solar, resultando em maior produção de matéria seca ao longo do seu desenvolvimento.

Producción de biomasa y valor nutritivo de líneas de soya forrajera [Glycine max L (Merr.)] en el noroeste de Puerto Rico.

Se evaluaron diez líneas de soya forrajera [Glycine max L. (Merr.)] en dos fechas de siembra (FS), septiembre y enero, y dos edades fisiológicas de cosecha (EFC), R2 (plena floración) y R5.4 (mayoría de vainas con 51 a 75% de llenado), en un área total de 496 m2 de un suelo Oxisol, bajo condiciones de temperatura y precipitación no limitantes al crecimiento del cultivo. El diseño experimental fue de parcelas divididas en bloques completos al azar, constituyendo FS las parcelas completas, EFC las subparcelas, y las líneas de soya las sub-subparcelas. El rendimiento de materia seca (RMS) fue mayor (P menor que 0.01) con R5.4 que con R2 (6,452 vs. 5,436 kg/ha), osciló (P menor que 0.058) de 5,300 a 6,573 kg/ha entre las líneas de soya y no difirió entre las dos FS. La densidad de siembra, alrededor de 260,000 plantas por hectárea, no estuvo afectada por ninguno de los tres factores principales. La altura de las plantas osciló (P menor que 0.01) de 84.2 a 93.2 cm entre las líneas de soya; difirió (P menor que 0.05) entre las FS (89.2 cm, septiembre vs. 87.5 cm, enero) y (P menor que 0.01) entre las EFC (72.4 cm, en R2 vs. 104.3 cm en R5.4); y acusó efecto (P menor que 0.01) de todas las dobles y de la triple interacción entre los tres factores. La proporción de hoja en la MS total fue mayor (P menor que 0.01) con EFC R2 que con R5.4 (44.1 vs. 41.1%) y hubo interacción (P menor que 0.05) de EFC x línea. Referente a la composición química porcentual del forraje, la proteína bruta (PB) varió entre las líneas de soya (P menor que 0.05) y entre las EFC (P menor que 0.01) y estuvo afectada (P menor que 0.01) por la interacción de estos dos factores (29.6 a 33.6, R2; 23.1 a 26.7, R5.4). La fibra detergente ácido (FDA) se comportó como la PB en cuanto a la significación de las variables independientes (21.0 a 25.6, R2; 26.2 a 33.3, R5.4); mientras la fibra detergente neutro (FDN) no difirió entre las líneas de soya, pero fue mayor (P menor que 0.01) con R5.4 que con R2 (41.0 vs. 33.5) y estuvo afectada por la interacción de EFC x línea. Se concluye que, tanto en características agronómicas como en composición química, todas las líneas de soya evaluadas tuvieron un comportamiento aceptable, pero se destacaron las SF-6, SF-24, SF-50, SF-88 y SF-110 más que las SF-1, SF-2, SF-22, SF-57 y SF-72; la cosecha a R5.4 fue ventajosa para aprovechar un mayor RMS sin sacrificar demasiado la excelente composición química que caracteriza el forraje de R2; y los efectos de la FS no fueron de mucha magnitud.

Influence of cultivar, sowing date and maturity at harvest on yield, digestibility, rumen fermentation kinetics and estimated feeding value of maize silage

SUMMARYTwo maize hybrid cultivars, early (Cisko FAO 300) and late maturing (Arma FAO 700), were sown on three different dates (March, April or May) and harvested at two stages of maturity (kernel milk line (ML) scores of 1/4 &lt; ML &lt; 1/3 or 1/2 &lt; ML &lt; 2/3) in the western Po plain (Italy) in 2008. Yield, chemical composition andin vitrodigestibility and fermentation kinetics of pre-ensiled whole-crop maize and of silage were measured. Cultivar and sowing date influenced the dry matter (DM) yield of whole-plant maize, with DM yield being 40% higher in Arma than in Cisko, and DM yield decreasing with later sowing dates. Later maturity increased DM concentration at harvest for both hybrids, due to differences in kernel development. The neutral detergent fibre (NDF) content declined and starch increased as plants matured. Digestibility was estimatedin vitrofollowing the Ankom procedure. Rate and extent of ruminal degradation were estimated from gas production (GP) profiles during incubation in diluted rumen fluid. Cultivar, planting date and maturity had no effect onin vitroDM digestibility of pre-ensiled whole-crop maize, but following 240 days of ensiling significant differences between cultivars in digestibility were detected. GP kinetic parameters differed between cultivars for pre-ensiled whole-crop maize, with Cisko having higher asymptotic GP but lower fractional fermentation rates and longer lag times than the Arma hybrid. GP volumes were greater as sowing or harvest dates were delayed. Energy value and milk production were estimated using the Milk2006 Model. With the pre-ensiled whole-crop maize, a 38% greater milk yield/ha was expected with Arma than with Cisko, matching the 40% greater DM yield. The same trend was observed in maize silage, where cultivar and planting date affected milk production/ha, with greater values for Arma than for Cisko and lower values for the latest planting date. Optimal management practices, including decision making on planting and harvest time and hybrid cultivar selection, can influence the yield and nutritive value of maize silage.

Screening Perennial Warm-Season Bioenergy Crops as an Alternative for Phytoremediation of Excess Soil P

A recent alternative strategy to reduce environmental problems associated with P transport from agricultural soils is the use of bioenergy crops to remediate excess soil P. In addition to the positive impacts associated with P mitigation, harvested biomass used as a renewable energy source can also offset the cost associated with plant-based P remediation strategies. The objective of this study was to identify potential crop species that can be used for remediation of soil P and as a cellulosic feedstock for production of renewable energy in South Florida. Fifteen crop entries were investigated for their potential to remove P from a P-enriched soil. Dry matter (DM) yield varied among crop species with greatest yield observed for elephantgrass (Pennisetum purpureum Schum.) and sugarcane (Saccharum spp.) (43 and 39 Mg ha−1 year−1, respectively). Similarly, greater P removal rates were observed for elephantgrass (up to 126 kg P ha−1 year−1 in 2008) followed by sugarcane (62 kg P ha−1 year−1 in 2008). Although there was no effect (P = 0.45) of crop species on P reduction in the soil, soil P concentrations decreased linearly during the 3-year study. Because of its relatively greater DM yield and P removal rates, elephantgrass was shown to be a good candidate for remediation of excess soil P in South Florida Spodosols.

Soil microbial community structure and microbial activities in the root zone of Nothapodytes nimmoniana

Camptothecin (CPT) is a bioactive secondary metabolite of Nothapodytes nimmoniana (Graham) Mablerley and has strong antitumor activity due to its ability to inhibit DNA topoisomerase I. In this study the changes of soil chemical and microbiological properties in the root zone of N. nimmoniana under application of two different nitrogen (N) fertilizers with different rates were investigated. There were seven treatments consisting of four rates of chemical N fertilizer, two rates of organic fertilizer, and a control where there was no fertilization and planting. Two-year-old N. nimmoniana plants were used in the study. Ten months later the plants were harvested and the soils were collected for analyses of chemical properties, microbial carbon (MBC), microbial nitrogen (MBN), respiration rate (basal respiration), phospholipid fatty acids of microorganisms, and six soil enzyme activities. Results showed that higher rates of N fertilizer resulted in greater dry matter yield of N. nimmoniana, while N rates had no significant effect on the CPT concentrations of roots and the whole plants except for lower CPT concentration in the N4 (applying 10.0 g N per pot in total) treatment. There was no difference in chemical properties, MBC, MBN, respiration rate, and N mineralization rate of soils among chemical N fertilizer treatments. N. nimmoniana decreased the soil microbial communities as compared with the control. Compared with bacteria and actinomyctes, fungi were more affected by N. nimmoniana cultivation. In contrast, N. nimmoniana had no effect on the activities of soil enzymes. Different rates of chemical N fertilizer had the same effect on the microbial communities. However, the application of organic fertilizer demonstrated a significant amelioration on the adverse effect of the soil microbial communities resulting from the cultivation of N. nimmoniana.