A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surfa...A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3- -N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.展开更多
Excessive nitrogen （N） fertilization of high value horticultural crops is a common problem that not only increases the cost to farmers, but also negatively affects crop growth and the environment. A three-year field...Excessive nitrogen （N） fertilization of high value horticultural crops is a common problem that not only increases the cost to farmers, but also negatively affects crop growth and the environment. A three-year field experiment was conducted in an intensive kiwifruit orchard in Shaanxi Province, China to compare the effects of reduced N fertilization applied as urea （U）, and controlled release urea （CRU） on the N nutrition of kiwi vines, fruit yield and quality, and nitrate-N accumulation in the soil profile. The three treatments included a conventional N application rate （CF-U, 900 kg N ha-1 yr-1 as urea）, two reduced N fertilization treatments where the amount of N fertilizer applied as U and CRU was reduced by 25％ in 2013 and 2014, and by 45％ in 2015. The 25 and 45％ reduced N treatments had no adverse effects on the N concentrations in leaves and pruning branches and the fruit yield and quality of kiwi vines. However, they significantly enhanced the partial factor productivity of applied N （PFPN） and the economic benefits, and reduced nitrate accumulation in the 0-200 cm soil profile. The same benefits of reduced N fertilization were observed for both the U and CRU treatments, but the CRU treatment had the added benefit of decreasing the loss of nitrate through leaching. We concluded that the current level of N fertilization in kiwi orchards is very excessive, and reducing the N fertilizer rate by 25-45％ could not only guarantee fruit yield, but also reduce N accumulation and loss.展开更多
Potassium(K) and magnesium(Mg) levels and their balances are two factors affecting the growth of plant. However, the responses of different crop cultivars to K/Mg ratios are less clear. This study was aimed at assessi...Potassium(K) and magnesium(Mg) levels and their balances are two factors affecting the growth of plant. However, the responses of different crop cultivars to K/Mg ratios are less clear. This study was aimed at assessing the different responses of tomato(Solanum Lycopersicum L.) cultivars to the different K/Mg supply ratios. Three tomato cultivars(Zhongza 9(ZZ), Gailiangmaofen(MF), and Jinpengchaoguan(JP)) were grown in pots with three different K+/Mg2+ratios(4:0, 4:1 and 8:1, represented by K/Mg4:0, K/Mg4:1, and K/Mg8:1, respectively). Compared with K/Mg4:1treatment, the leaf chlorophyll content, net photosynthetic rate, and total biomass of tomato seedlings under K/Mg4:0treatments were decreased by 69.7, 89.1, and 53.1%, respectively. The Mg deficiency symptoms were observed when the Mg content in shoot became lower than 4 mg g–1DW. Compared with K/Mg4:1treatment, total biomass of tomato seedlings of K/Mg8:1treatment was decreased by 21.6%; the shoot and root Mg contents were decreased by 10.4 and 21.8%, respectively; and Mg uptake of tomato was reduced by 34.1%. There were significant differences in biomass and Mg uptake for the three cultivars between the different K+/Mg2+treatments. The Mg uptake of the three different cultivars ranked as ZZ>JP>MF under Mg deficiency and high K condition. In conclusion, the growth and Mg uptake and allocation of tomato were influenced significantly by imbalance K and Mg supply. JP and ZZ were the cultivars with the highest efficiency in Mg uptake.展开更多
为探究黄土高原地区日光温室果蔬栽培中氨挥发特征,在陕西省杨凌区选择当地典型的日光温室,设置4个不同的水氮处理,采用密闭式间歇抽气法监测番茄-西瓜轮作季的氨挥发特征.结果表明:日光温室栽培土壤氮素转化快,施氮处理施肥后第1～2天...为探究黄土高原地区日光温室果蔬栽培中氨挥发特征,在陕西省杨凌区选择当地典型的日光温室,设置4个不同的水氮处理,采用密闭式间歇抽气法监测番茄-西瓜轮作季的氨挥发特征.结果表明:日光温室栽培土壤氮素转化快,施氮处理施肥后第1～2天氨挥发出现峰值,氨挥发峰值为0.26～2.02 kg N·hm^(-2)·d^(-1),7 d左右各处理氨挥发通量相近;施氮处理间氨累积排放量无显著差异;相同施氮量条件下,降低灌溉量氨累积排放量两季平均增加了46.7%;不同种植季氨平均排放通量和累积排放量均表现为西瓜季高于番茄季,西瓜季高温促进了氨排放;土壤铵态氮含量、土壤孔隙含水量、0～5 cm地温和温室气温均对氨排放通量有极显著影响,而土壤pH值与氨挥发通量呈显著负相关关系.不同种植季氨挥发通量和累积排放量存在差异,降低施氮量可减少氨排放,相同施氮量条件下降低灌溉量增加了氨排放.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 30230230 and 30370288)the NationalKey Laboratory for Soil Erosion and Dryland Farming on the Loess Plateau (No. 10501-116).
文摘A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3- -N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.
基金supported by the National Key Technologies R&D Program of China during the 12th Five-Year Plan period (2012BAD15B04)the National Natural Science Foundation of China (31372137,41671295)+1 种基金jointly supported by the Department for Environment,Food and Rural Affairs (Defra) of UKthe Ministry of Agriculture of China under the Sustainable Agriculture Innovation Network (SAIN)
文摘Excessive nitrogen （N） fertilization of high value horticultural crops is a common problem that not only increases the cost to farmers, but also negatively affects crop growth and the environment. A three-year field experiment was conducted in an intensive kiwifruit orchard in Shaanxi Province, China to compare the effects of reduced N fertilization applied as urea （U）, and controlled release urea （CRU） on the N nutrition of kiwi vines, fruit yield and quality, and nitrate-N accumulation in the soil profile. The three treatments included a conventional N application rate （CF-U, 900 kg N ha-1 yr-1 as urea）, two reduced N fertilization treatments where the amount of N fertilizer applied as U and CRU was reduced by 25％ in 2013 and 2014, and by 45％ in 2015. The 25 and 45％ reduced N treatments had no adverse effects on the N concentrations in leaves and pruning branches and the fruit yield and quality of kiwi vines. However, they significantly enhanced the partial factor productivity of applied N （PFPN） and the economic benefits, and reduced nitrate accumulation in the 0-200 cm soil profile. The same benefits of reduced N fertilization were observed for both the U and CRU treatments, but the CRU treatment had the added benefit of decreasing the loss of nitrate through leaching. We concluded that the current level of N fertilization in kiwi orchards is very excessive, and reducing the N fertilizer rate by 25-45％ could not only guarantee fruit yield, but also reduce N accumulation and loss.
基金supported by the National Natural Science Foundation of China (41671295)the Agricultural Scientific and Technological Project in Shaanxi Province,China (2014K01-14-03)
文摘Potassium(K) and magnesium(Mg) levels and their balances are two factors affecting the growth of plant. However, the responses of different crop cultivars to K/Mg ratios are less clear. This study was aimed at assessing the different responses of tomato(Solanum Lycopersicum L.) cultivars to the different K/Mg supply ratios. Three tomato cultivars(Zhongza 9(ZZ), Gailiangmaofen(MF), and Jinpengchaoguan(JP)) were grown in pots with three different K+/Mg2+ratios(4:0, 4:1 and 8:1, represented by K/Mg4:0, K/Mg4:1, and K/Mg8:1, respectively). Compared with K/Mg4:1treatment, the leaf chlorophyll content, net photosynthetic rate, and total biomass of tomato seedlings under K/Mg4:0treatments were decreased by 69.7, 89.1, and 53.1%, respectively. The Mg deficiency symptoms were observed when the Mg content in shoot became lower than 4 mg g–1DW. Compared with K/Mg4:1treatment, total biomass of tomato seedlings of K/Mg8:1treatment was decreased by 21.6%; the shoot and root Mg contents were decreased by 10.4 and 21.8%, respectively; and Mg uptake of tomato was reduced by 34.1%. There were significant differences in biomass and Mg uptake for the three cultivars between the different K+/Mg2+treatments. The Mg uptake of the three different cultivars ranked as ZZ>JP>MF under Mg deficiency and high K condition. In conclusion, the growth and Mg uptake and allocation of tomato were influenced significantly by imbalance K and Mg supply. JP and ZZ were the cultivars with the highest efficiency in Mg uptake.
文摘为探究黄土高原地区日光温室果蔬栽培中氨挥发特征,在陕西省杨凌区选择当地典型的日光温室,设置4个不同的水氮处理,采用密闭式间歇抽气法监测番茄-西瓜轮作季的氨挥发特征.结果表明:日光温室栽培土壤氮素转化快,施氮处理施肥后第1～2天氨挥发出现峰值,氨挥发峰值为0.26～2.02 kg N·hm^(-2)·d^(-1),7 d左右各处理氨挥发通量相近;施氮处理间氨累积排放量无显著差异;相同施氮量条件下,降低灌溉量氨累积排放量两季平均增加了46.7%;不同种植季氨平均排放通量和累积排放量均表现为西瓜季高于番茄季,西瓜季高温促进了氨排放;土壤铵态氮含量、土壤孔隙含水量、0～5 cm地温和温室气温均对氨排放通量有极显著影响,而土壤pH值与氨挥发通量呈显著负相关关系.不同种植季氨挥发通量和累积排放量存在差异,降低施氮量可减少氨排放,相同施氮量条件下降低灌溉量增加了氨排放.
