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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In China, the freeze-thawing phenomenon occurs in the northeastern region, which happens in autumn, winter and early spring and can affect the structure as well as physical and chemical properties of the black soil. The concentrations and speciation of nutrition elements (nitrogen and phosphor) in black soil are also influenced by the freeze-thawing, which may have effects on the fertility of the soil or even result in eutrophication. In order to find out the change of nitrogen and phosphor concentrations and availability in black soil with various levels of fertilizers under freeze-thawing condition, a simulation freeze-thawing experiment was proposed in this paper. Various levels of inorganic nitrogen and phosphor fertilizers as well as organic fertilizer were applied in 10 maize plots based on the results of investigation on agricultural production in Heilongjiang Province and the specific circumstance of the present experiment. Then the black soil samples were collected from the 10 plots and put through simulative freeze-thawing cycles in the lab. After each cycle, the parameters of the soil samples were analyzed, including the soil properties (moisture contents, mass fraction of organic matters) and mass fractions of total nitrogen, available nitrogen, total phosphor and available phosphor. It was shown that freeze-thawing process could increase the moisture contents of soil samples for all the 10 treatments (P<0.05). And under the freeze-thawing condition, the inorganic and organic fertilizers could improve the water holding capacity, resulting in higher moisture contents than the unfertilized soil (P<0.05). The mass fraction of organic matters in soil samples for all the 10 treatments significantly decreased after 5 freeze-thawing cycles, and the highest reduction rate after 5 cycles was obtained in the sample with only organic fertilizer (29.7%, P<0.05). For the samples with inorganic fertilizers, concentrations of total nitrogen decreased significantly after 5 freeze-thawing cycles (P<0.05), indicating that freeze-thawing process could result in the loss of total nitrogen in black soil. The reduction rate of total nitrogen concentration after 5 freeze-thawing cycles was positively related to the quantity of inorganic nitrogen fertilizer (r=0.9899) when the level of inorganic phosphor fertilizer was constant. When organic fertilizer was applied, the total nitrogen concentrations in soil samples after 5 freeze-thawing cycles changed insignificantly, therefore the loss of total nitrogen could be inhibited. For all the samples except the one where inorganic nitrogen fertilizer level was the largest, concentrations of available nitrogen increased significantly after 5 freeze-thawing cycles (P<0.05), while the application of inorganic nitrogen and phosphor fertilizers could inhibit the increase of available nitrogen concentration. The increasing rate of available nitrogen concentration after 5 freeze-thawing cycles was negatively related to the quantity of inorganic nitrogen fertilizer (r=-0.9675) when the level of inorganic phosphor fertilizer was constant. When the organic fertilizer was applied in the soil samples, the increasing rates of available nitrogen mass fraction were the highest among all the treatment (20.8% and 23.6%, P<0.05), indicating that application of organic fertilizer could improve the availability of nitrogen in black soil. The concentrations of total phosphor in samples for all the treatments changed insignificantly after the freeze-thawing cycles. For all the 10 treatments, the concentrations of available phosphor in soil samples increased after 5 freeze-thawing cycles (P<0.05). The application of either inorganic or organic fertilizer in the experiment could make the increasing rate higher, and the highest occurred when organic fertilizer were applied (23.4% and 27.1%, P<0.05), suggesting that the availability of phosphor in black soil could be higher when organic fertilizer was applied. In conclusion, during the agricultural practice of black soil in cold regions under freeze-thawing condition, the quantity of organic fertilizer applied should increase appropriately in order to inhibit the loss of total nitrogen, as well as to improve the availability of nitrogen and phosphor, so as to maintain the fertility of black soil and lower the risk of eutrophication. [ABSTRACT FROM AUTHOR]

Soil respiration is mediated by microbial activities, temperature, humidity and other environmental factors in soil. The increase in use of microbial organic fertilizer and drip irrigation in greenhouse production could alter soil micro-environment, particularly the rhizosphere, thereby leading to a change in soil respiration. This paper investigated the response of soil respiration to different combinations of drip irrigation amounts and microbial organic fertilizer applications. We experimentally compared three irrigation amounts 15, 18 and 21 mm – associated with three microbial organic fertilizer applications 2800, 3600 and 4400 kg/hm². The treatment with inorganic fertilizer application served as the control. In each treatment, we measured soil respiration rate and accumulated carbon emission, as well as other determinants. The soil temperature and humidity were measured following the soil respiration measurement using the delta-T sensor (delta-T company, UK); soil organic matter was measured using the potassium dichromate sulfuric acid oxidation external heating method; the activity of dehydrogenase was determined using the TTC colorimetry method; the activity of urease was determined by the phenol sodium colorimetry method; the activity of catalase was determined by the KMnO4 volumetric method. We analyzed the responsive change in soil respiration to these determinants and root biomass. The results showed that, compared to the CK, drip irrigation and microbial organic fertilization improved soil organic matter and increased the activities of dehydrogenase, urease and catalase by 11.6%-27.6%, 8.0%-27.7% and 1.8%-11.2%, respectively; the increase in urease activities was at significant level (p<0.05). The soil respiration rate was positively correlated to the root biomass, temperature and organic matter content at significant level of p<0.01, and to the enzymatic activities at significant level of p<0.05. Among all treatments, irrigating 18 mm of water and applying 4400 kg/hm² of microbial organic fertilizer produced the highest root biomass, reaching 394 g/m² 120 days after the transplanting. Overall, combining drip irrigation and microbial organic fertilization increased root biomass by 25.9%-43.4%, compared to the CK. When irrigation amount was 15 and 18 mm, the carbon emission increased significantly (p<0.05) when the fertilizer application increased from 3600 kg/hm² to 4400 kg/hm². The cumulative carbon emission peaked at 415.2 g/m² when the irrigation amount was 18 mm and the microbial fertilization was 4400 kg/hm², significantly higher than that under other treatments (p<0.05). The lowest cumulative carbon emission was from the CK, being 255.3 g/m² only. In summary, this study showed that drip irrigation and microbial organic fertilization combined to impact soil carbon emission by changing organic matter content and root biomass in the soil. Our results have important implications for improving ecological cultivation in greenhouse production. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Songnen plain is the main grain strategy reserve area of China, and it is also one of the three largest soda saline-alkali soil regions in the world. Soil salinization severely restricts the sustainable development of agriculture and the improvement of people's living standards. The land consolidation major projects officially launched in the west of Jilin Province in 2007 provides an effective way for comprehensive controlling salinity land. In the process of land consolidation, one of the most important problems need to be addressed was how to combine land consolidation with soil improvement to realize the purpose of increasing cultivated land areas and improving salinity soil. In order to study the Western Songnen Plain land consolidation effect on improving salinity soil, this paper took the land consolidation project in Zhenlai county of Jilin Province as study area, selected the original cultivated land, saline-alkali land and newly-added cultivated land as plots, adopted the methods of classical statistical analysis and canonical correspondence analysis to comparative study the differences of soil physical and chemical properties and soil ionic composition of different plots. And then we put forward related suggestions for land consolidation and improving salinity soil. The results showed that, in 0-20 and >20-40 cm soil layer, soil electrical conductivity of newly-added cultivated land was significantly decreased by 44.9% and 37.0% than saline-alkali land (P<0.05), but significantly higher than original cultivated land by 35.7% and 58.6%. The total actions and total anions of newly-added cultivated land were significantly lower than saline-alkali land (P<0.05). The exchange sodium percentage of saline-alkali land was around 38% and pH value was close to 10.0, that was classified to severe salinity soil. While the newly-added cultivated land soil exchange sodium percentage was 18.0% and 21.6%, and soil pH value was less than 9.0, that was classified to moderate salinity soil and close to the original cultivated land. Newly-added cultivated soil organic matter was higher than saline-alkali land by 33.4% and 61.3% significantly (P<0.05), but it was significantly lower than original cultivated 21.5% in 0-20 cm soil layer. Newly-added cultivated soil cation exchange capacity was increased by 16.7% and 25.1% than saline-alkali land (P>0.05), and it's slightly higher than original cultivated land. Canonical correspondence analysis results showed that soil physical and chemical properties and ionic composition had significant correlation with plot type distribution. Plot type changed from saline-alkali land to newly-added cultivated land was the process of soil salinization indices decreasing and fertility indices rising in the level of soil physical and chemical properties, and also the process of bicarbonate ion, carbonate ion and sodium ion content reduction in the level of soil ionic composition. Overall, the land consolidation project in Western Songnen Plain could improve salinity soil effectively, but the soil quality of newly-added cultivated land is still lower than the original cultivated land. Therefore, we suggest to improve salinity soil better through improvement of irrigation and drainage system, reasonable land leveling measure and scientific farming. [ABSTRACT FROM AUTHOR]