Organic matter accumulation and fertilizer-induced acidification interact to affect soil microbial and enzyme activity on a long-term sugarcane management experiment     

M. H. Graham  R. J. Haynes 《Biology and Fertility of Soils》2005,41(4):249-256

The effects of crop residue management and fertilizer applications on the size and activity of the microbial community and the activity of exocellular enzymes involved in mineralization of C, N, P and S were examined on a long-term (60 years) field trial under sugarcane situated at Mount Edgecombe, South Africa. Treatments at the site included pre-harvest burning with harvest residues removed (B), burning with harvest residues (unburnt tops) left on the soil surface (B_t) and green cane harvesting with retention of a trash blanket (T). Plots were either fertilized annually with N, P and K or unfertilized. The size and activity of the microbial community and the activity of soil enzymes assayed increased with increasing inputs of crop residues (B < B_t < T) and this effect was evident to a depth of 30 cm. The metabolic quotient was decreased by inputs of both crop residues and fertilizers. Annual fertilizer additions did not affect basal respiration, increased fluorescein diacetate (FDA) hydrolysis rate and acid phosphatase, invertase and protease activities and decreased arginine ammonification rate and dehydrogenase, alkaline phosphatase, arylsulphatase and histidase activities. These effects were attributed to an interaction between the positive effect of fertilizer in increasing the size of the microbial biomass and the negative effect of fertilizer-N-induced soil acidification on microbial activity and on the activity of exocellular enzymes. Such results demonstrate the importance of using a range of measurements of microbial and enzyme activity when determining the effects of management on soil microbial and biochemical properties.  相似文献   

Comparative effects of annual and permanent dairy pastures on soil physical properties in the Tsitsikamma region of South Africa   总被引：1，自引：0，他引：1  

R.M. Milne  R.J. Haynes 《Soil Use and Management》2004,20(1):81-88

Abstract. The effects of grazed, annual ryegrass pasture (annually tilled with a rotary cultivator) and permanent kikuyu pasture were compared with that of undisturbed native vegetation at four sites in the Tsitsikamma region, South Africa. Soil organic carbon content, aggregate stability, saturated hydraulic conductivity, air permeability, root length density and rooting depth were all less under ryegrass than kikuyu pasture. There was, however, no consistent effect of pasture-type on pore size distribution or penetrometer resistance. Differences in penetrometer resistance were most obvious in the 10–30 cm layer with subsurface compaction being evident at some sites under both types of pasture. This was attributed to the treading effects of grazing cattle plus formation of a compacted layer at the depth of tillage under ryegrass pastures. Subsoil tillage of a ryegrass pasture resulted in a substantial reduction in penetrometer resistance in the compacted 10–20 cm layer and increases in hydraulic conductivity, air permeability, root length density and rooting depth. We conclude that conversion from conventional to zero tillage is a potential way of improving the sustainability of annual pasture production and that the extent of subsoil compaction under both pasture types needs further investigation.  相似文献   

Barley yield and soil microbial and enzyme activities as affected by contamination of two soils with lead, zinc or copper   总被引：5，自引：0，他引：5  

O. N. Belyaeva  R. J. Haynes  O. A. Birukova 《Biology and Fertility of Soils》2005,41(2):85-94

The effects of increasing rates of Pb, Zn and Cu on extractable heavy metal levels, barley yields, basal respiration and the activities of catalase, urease, invertase and acid phosphatase were investigated in two soils in a 2-year greenhouse experiment. In the first year, barley yields were decreased by increasing additions of Pb, Zn and Cu. In the second year, increased yields were recorded at lower rates of addition of all three metals in both the chestnut and chernozem soils. Yield depressions were most marked for added Cu and least marked for Pb but, in contrast, accumulation of heavy metals in grain, in excess of recommended limits, was most pronounced for Pb and did not occur for Cu. Increasing rates of all three metals caused a decrease in basal respiration; the degree of inhibition was generally greater in the second than in the first year. After 1 year of incubation, increasing rates of addition of metals reduced all tested enzyme activities. However, after 2 years, the pattern of response was more complex, with increases in enzyme activities being noted at lower rates of addition of all three metals. In general, invertase and urease activities were more markedly inhibited by heavy metal contamination than those of catalase and phosphatase. Ammonium acetate-extractable heavy metal concentrations in soils were less after 2 years than 1 years reaction time due to their transformation into less labile forms. Significant negative correlations between grain yield, basal respiration and enzyme activities were observed in both years.  相似文献   

Disruption of the caudal component of the reciprocal apparatus in two horses     

R S Shoemaker  G S Martin  D J Hillmann  P F Haynes  J R McClure  H L Schneiter 《Journal of the American Veterinary Medical Association》1991,198(1):120-122

Two horses became acutely lame following a fall during strenuous exercise and were diagnosed as having disruption of the caudal component of the reciprocal apparatus. Clinical signs consisted of lameness of the right pelvic limb, characterized by flexion of the hock and simultaneous extension of the stifle. Radiography revealed an avulsion fracture from the supracondylar tuberosity and fossa of the distal portion of the femur in one horse. Clinical and radiographic findings indicated avulsion of the lateral origin of the gastrocnemius and superficial digital flexor muscles. Treatment consisted of stall rest, limb immobilization, and phenylbutazone administration. One horse recovered to soundness and the other deteriorated and was euthanatized.  相似文献   

The March 1998 issue of Agriculture and Human Values     

R.P. Haynes 《Agriculture and Human Values》1998,15(1):1-2

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Plasma progesterone concentration in the hen in relation to the ovulatory cycle     

N B Haynes  K J Cooper  M J Kay 《British poultry science》1973,14(4):349-357

The concentration of peripheral plasma progesterone was measured by a double isotope derivative assay in hens slaughtered at various stages during the ovulatory cycle. A peak value was obtained 2 to 6 h before ovulation and basal levels were reached at ovulation. No secondary peaks were observed during the cycle. Similar results were obtained using a protein‐binding assay on plasma from individual birds taken serially during the cycle. Birds which did not ovulate on a particular day showed no peak of progesterone. In two birds sampled at the beginning of a laying cycle, the progesterone peak was of longer duration.  相似文献   

Cross-sectional area of the aditus laryngis and rima glottidis before and after transection of the left recurrent laryngeal nerve in the horse   总被引：1，自引：0，他引：1  

G S Martin  R E Beadle  P F Haynes  J W Watters 《American journal of veterinary research》1986,47(2):422-425

The ventral-to-dorsal height of the rima glottidis was measured from lateral pharyngeal radiographs after correction for magnification. The rima glottidis height was used to enlarge accurately endoscopic photographs of 5 horses taken before and after transection of the left recurrent laryngeal nerve. Areas of the rima glottidis and aditus laryngis were measured, using a computerized digitizer. Mean area of the aditus laryngis was 1,908 mm2 before neurectomy and 1,346 mm2 after neurectomy (P = 0.025). Mean area of the rima glottidis was 1,198 mm2 before neurectomy and 805 mm2 after neurectomy (P = 0.025). Mean width of the rima glottidis was 31 mm before neurectomy and 20 mm after neurectomy (P = 0.001). Significant differences were not found between the pre- and postneurectomy heights of the rima glottidis.  相似文献   

Infectivity of Cryptosporidium sp isolated from wild mice for calves and mice   总被引：4，自引：0，他引：4  

P H Klesius  T B Haynes  L K Malo 《Journal of the American Veterinary Medical Association》1986,189(2):192-193

A study was conducted to determine the incidence of cryptosporidiosis in wild mice (Mus musculus) and the infectivity of oocysts from their feces for susceptible calves. The presence of oocysts and the duration of shedding of oocysts in the feces were evaluated in 115 wild mice. Approximately 30% of the mice shed Cryptosporidium sp oocysts, without evidence of clinical infection; recurrence of oocyst shedding was found in about 50% of the mice. Oocysts from the feces of naturally infected mice were infective for calves and mice. Calves began shedding oocysts at 7 days and shed oocysts for about 10 days. Nonfatal, clinical cryptosporidiosis developed in 7 infected calves. The mice began shedding oocysts at 6 days and shed oocysts for 12 days. Fatalities or clinical infection did not develop in 5 infected mice. The results indicated that Cryptosporidium-infected wild mice may be a source of cryptosporidiosis in susceptible calves.  相似文献   

Effect of intracarotid infusion of prostaglandin F2alpha on plasma luteinizing hormone, testosterone and glucocorticoid concentrations in bulls     

N B Haynes  T E Kiser  H D Hafs  T D Carruthers  W D Oxender  M S McCarthy 《Journal of animal science》1977,45(5):1102-1107

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Review on physiological pathways of foliar absorption     

R.J. Haynes  K.M. Goh 《Scientia Horticulturae》1977,7(4):291-302

This review concerns the movement of foliar-applied substances through the leaf with an emphasis on plant nutrients. The movement of substances through the cuticle is well documented and is only outlined here. Knowledge of subsequent movement of substances throughout the leaf is rather sketchy. The various possible pathways of movement are outlined and discussed. Both symplastic and apoplastic movement seem possible. Ionic uptake and movement within leaves is complicated by photosynthesis which is occurring within many of the cells and by complex ionic movement associated with stomatal movement.  相似文献