Evaluation of technologies for sequestering carbon in agricultural land by using organic filter underdrains

Technology for storing carbon in the subsoil of agricultural land using organic filter materials in underdrains was evaluated as an activity for sequestering CO₂ to mitigate global warming. First, the quantity of carbon remaining in wood chips and rice husks in underdrains was determined over 11 years after construction. Moreover, the quantity of CO₂ emissions from the construction of two underdrain types was calculated. Then, a survey was conducted to investigate the effect on greenhouse gas emissions of the filter material. The results indicate that greenhouse gas emissions would not increase. The quantity of storage carbon in the wood chip filter material of underdrains during their 15-year service life was estimated to be 6.76 tCO₂eq ha^?1. Rice husks, in contrast, were found ineffective in storing carbon. Therefore, the selection of the filter material for underdrains is important. The value of storage carbon in the wood chip filter material is similar to the amount of carbon sequestered by no-till farming, which is now being implemented as a global warming countermeasure based on soil management in agricultural land.     

Phospholipase A<Subscript>1</Subscript> activity of crude enzyme extracted from the ovaries of skipjack tuna

The phospholipid class composition, fatty acid composition and phospholipase A₁ (PLA₁) activity from the ovaries of skipjack tuna were compared with those of six other species of marine fish. In the skipjack ovaries, the lysophosphatidylcholine (LPC) proportion for the phospholipid, the docosahexaenoic acid (DHA) percentage for the total fatty acids of the phospholipids and the PLA₁ activity of the crude enzyme were the highest among those of the seven species. The optimum pH and temperature for the PLA₁ activity of the crude enzyme from the skipjack ovaries were in the range of pH 6–7 and 20–30°C, respectively, and calcium ions were not required. As a substrate, phosphatidylcholine was more easily hydrolyzed than phosphatidylethanolamine by this enzyme, and the plasmalogen-type phospholipid was much lower than the acyl-type phospholipid. After a 6-h hydrolysis reaction of the purified phospholipid extracted from the mixed ovaries of skipjack and yellowfin tuna by this enzyme, the LPC ratio of the phospholipid increased from 20 to 72.6% and the percentage of DHA for the total fatty acids of the phospholipid also increased. Thus, skipjack ovaries might possibly be used as a source of PLA₁.     

Drainage and irrigation performance of hybrid ditches in converted paddy fields under winter wheat cultivation in Hokkaido

Paddy fields converted into winter wheat fields in Hokkaido, Japan, receive extremely high snowfall, creating a risk of flood damage to crops in spring due to waterlogging of snowmelt runoff and poor drainage. Meanwhile, in June there is relatively little rainfall, and a lack of moisture inhibits winter wheat growth. Therefore, we developed a method involving a series of 30-cm-deep ditches in agricultural fields to be used for drainage during the flood-prone period and for furrow irrigation during the dry period using water drawn from the canals that feed the paddy fields. The ditches are called ‘hybrid ditches’ as they are able to perform both drainage and irrigation functions. In this study, we investigated the optimal construction timing and spacing for hybrid ditches. We also evaluated their ability to improve the drainage and irrigation of winter wheat. We found that the optimal timing for digging hybrid ditches is immediately after sowing, and the inter-ditch spacing for irrigation should be 15 m or less. The hybrid ditches promoted increased soil temperature and healthy development of wheat plants by improving drainage during the flood-prone period. In addition, water was successfully supplied via the hybrid ditches to irrigate the fields in June. Under experimental conditions in which rainfall was excluded, grain yield was 10% higher and percent protein content was more than 1% point greater in the irrigated plot compared with the non-irrigated plot. Grain yield was also observed to increase by 3–29% in demonstration tests conducted at local farms. From these results, we conclude that hybrid ditches are capable of improving the growth and yield of winter wheat by improving drainage and providing irrigation in converted paddy fields in Hokkaido.     

Relationship between pulmonary arterial pressure and pulmonary thromboembolism associated with dead worms in canine heartworm disease.

To examine effects of thromboemboli due to dead worms on pulmonary arterial pressure (PAP), 20 to 50 dead heartworms were inserted into the pulmonary arteries of 4 heartworm uninfected dogs (uninfected group) and 11 dogs infected with heartworms (infected group). In the uninfected group, the mean PAP rose 1 week after worm insertion (10.9 to 166. mmHg), but it recovered by the 4th week. Clinical signs, hemodynamics and blood gas findings also deteriorated at the 1st week, but recovered at the 4th week. Angiographic and pathological findings indicated that blood flow recovered through the spaces between thromboemboli and vessel walls at the 4th week. The infected dogs were divided into three groups. In the infected-I group (5 dogs), the intimal lesions of the pulmonary arteries were slight, and clinical and laboratory findings showed changes similar to those of the uninfected group. In the infected-II group (4 dogs), the pulmonary arterial lesions were severe and the mean PAP was higher (25.7 mmHg) than in the uninfected group before worm insertion. An increase in PAP (34.1 mmHg) and worsening of clinical and laboratory findings were noticed till the 4th week. Thromboemboli adhered extensively to the vessel walls. Two dogs in the infected-III group died of severe dyspnea on the 9th and 10th day, and the mean PAP rose remarkably at the 1st week (from 19.4 to 28.2 mmHg). Severe pulmonary parenchymal lesions with edema or perforation were observed. From the above results, it was clarified that effects of dead worms on PAP and clinical signs depended on the severity of pulmonary arterial lesions before worm insertion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevention of adverse reactions following milbemycin D administration to microfilaremic dogs infected with Dirofilaria immitis

Some adverse reactions such as shock-like reaction and dirofilarial hemoglobinuria (caval syndrome) occasionally occurred in microfilaremic dogs following milbemycin D (Milbe) administration. This study was carried out to seek the prevention of these adverse reactions. In two groups containing 16 and 9 dogs respectively which were administered either chlorpheniramine maleate (1 mg/kg) or indomethacin (2.5 mg/kg) simultaneously with Milbe (1 mg/kg), the incidence of clinical signs such as the pale color of the visible mucous membranes, respiratory disorders, caval syndrome and shock-like reaction as well as changes in clinical parameters such as RBC and WBC counts, WBC profile and serum total protein, were almost equal to that observed in the group administered Milbe alone. In 41 dogs administered prednisolone (1 mg/kg) simultaneously with Milbe (1 mg/kg), no shock-like reaction was observed. Changes in clinical parameters were different from those in the group administered Milbe alone, whereas some clinical signs of adverse reactions, including caval syndrome, were observed. These results indicated that prednisolone was effective for prevention of the shock-like reaction in microfilaremic dogs induced by Milbe.