[Ammonia volatilization and nitrogen use efficiency in the field of fresh edible maize as affec-ted by different band fertilization depths of controlled-release urea]. / æŽ§é‡Šå°¿ç´ æ¡æ–½æ·±åº¦å¯¹é²œé£ŸçŽ‰ç±³ç”°é—´æ°¨æŒ¥å‘å’Œæ°®è‚¥åˆ©ç”¨çŽ‡çš„å½±å“.

A field experiment was conducted to examine the effects of controlled-release urea (CRU) application on ammonia (NH3) volatilization, nitrogen (N) use efficiency and fresh ear yield of fresh edible maize. The treatments included one control (CK: no N fertilizer application) and four different band fertilization depths (0, 5, 10, 15 and 20 cm). Results showed that NH3 volatilization from non-fertilization band and planting band mainly occurred in the first two weeks after the fertilization, which lasted for almost a month in the fertilization band. Compared to CK, surface broadcasted CRU (0 cm) significantly increased NH3 volatilization from wide-row non-fertilization band or planting band in field. Soil NH3 volatilization amounts ranged from 3.1 to 25.5 kg N·hm-2 with the different depths of CRU application treatments, accounting for 1.7%-14.2% of total N applied. The cumulative NH3 volatilizations were comparable among the depths of 10, 15 and 20 cm of CRU fertilization treatments, which were significantly decreased by 85.9%-87.8% and 67.0%-71.6% as compared with surface broadcasted CRU and 5 cm of CRU fertilization, respectively. The increases of CRU application depth within a certain extent could increase fresh ear yield, total nitrogen accumulation of plants during milking stage, partial factor productivity, agronomic efficiency and apparent recovery efficiency of nitrogenous fertilizer, and the maximum values of these indices were recorded for 15 cm depth. We concluded that CRU application at 15 cm depth would be the optimal practice in terms of reducing NH3 volatilization and improving N use efficiency of fresh edible maize.

[Effect of application of cow manure and green manure on corn yield and soil physical-chemical properties in land restoration area]. / 施用牛粪和绿肥对土地整治区玉米产量和土壤理化性质的影响.

The effects of cow manure and green manure on maize yield, soil respiration and soil physical-chemical properties in land restoration area was evaluated through field experiments. The results indicated that the maize yield and thousand-grain mass with cow manure were increased by 7.2%-29.9% and 2.5%-18.2%, respectively compared with the application of chemical fertilizer (CF), while the soil active organic carbon and organic matter contents of cow manure were 5.3%-34.6% and 8.0%-17.6% higher than that obtained in CF. The maize yield and thousand-grain mass were increased by 10.8%-15.6% and 4.5%-8.4% with application of green manure, respectively compared with CF. The content of active organic carbon in green manure was 14.1%-48.6% higher than that detected in CF. In the second year, the content of organic matter in green manure treatment was 7.2% higher than that of CF. The soil respiration rates under cow manure and green manure treatments increased by 20.0%-69.3% compared with CF. CF and green manure could improve the soil bulk density and increase the aggregate ratios of ＜0.01 mm and 0.05-1 mm fractions, respectively. On the other hand, the cow manure and green manure could decrease the soil total porosity and the capillary porosity. In conclusion, the application of cow manure and green manure in land restoration region could increase maize yield during the two consecutive seasons, which showed a positive response to improvement of soil physical-chemical properties.

[Nutrient spatial variability of tobacco soil restoration area and fertility suitability level evaluation].

By using geographic information system technology (GIS) and geostatistics methods, this paper studied the spatial variability of soil properties and available nutrients in the new regulation area units located in Qingjiangyuan modern tobacco agriculture science and technology park (Enshi, Hubei), suburb of Enshi City and the Baiyang base of Lichuan City, and further evaluation of the soil fertility suitability index (SFI) was carried out by use fuzzy mathematics. The results indicated that the effects of land restoration on the soil available phosphorus content variability and spatial distribution were very obvious, possibly due to the landform characteristics and restoration extent. The effect of land restoration on soil pH was small, however, serious soil acidification was detected in the soil sampled from Baiyang (pH < 5.5). Low SFI was found in 77.6%, 17.1% and 31.4% of the soils taken from the suburb, Baiyang and Qingjiangyuan, respectively. In conclusion, attentions should be paid on soil acidification in Baiyang, soil fertility and equalization in the suburb, and soil fertility in the region of Qingjiangyuan with low SFI.