Gravel-sand mulch has been used for centuries to conserve water in the Loess Plateau of north- western China. In this study, we assessed the influence of long-term （1996-2012） gravel-sand mulching of cultiv- ated so...Gravel-sand mulch has been used for centuries to conserve water in the Loess Plateau of north- western China. In this study, we assessed the influence of long-term （1996-2012） gravel-sand mulching of cultiv- ated soils on total organic carbon （TOC）, light fraction organic carbon （LFOC）, microbial biomass carbon （MBC）, total organic nitrogen （TON）, particulate organic carbon （POC）, mineral-associated organic carbon （MOC）, perma- nganate-oxidizable carbon （KMnO4-C）, and non-KMnO4-C at 0-60 cm depths. Mulching durations were 7, 11 and 16 years, with a non-mulched control. Compared to the control, there was no significant and consistently positive effect of the mulch on TOC, POC, MOC, KMnO4-C and non-KMnO4-C before 11 years of mulching, and these organic C fractions generally decreased significantly by 16 years. LFOC, TON and MBC to at a 0-20 cm depth in- creased with increasing mulching duration until 11 years, and then these fractions decreased significantly between 11 and 16 years, reaching values comparable to or lower than those in the control. KMnO4-C was most strongly correlated with the labile soil C fractions. Our findings suggest that although gravel-sand mulch may conserve soil moisture, it may also lead to long-term decreases in labile soil organic C fractions and total organic N in the study area. The addition of manure or composted manure would be a good choice to reverse the soil deterioration that occurs after 11 years by increasing the inputs of organic matter.展开更多
地表覆盖能够减少土壤蒸发,对土壤保水、保墒有重要意义。本文基于显热平衡原理,探究了石子覆盖对近表层土壤内部蒸发的影响。应用热脉冲技术测定的热参数和土壤温度得到土壤内部蒸发速率、显热通量、土层上下部显热通量差、潜在汽化热...地表覆盖能够减少土壤蒸发,对土壤保水、保墒有重要意义。本文基于显热平衡原理,探究了石子覆盖对近表层土壤内部蒸发的影响。应用热脉冲技术测定的热参数和土壤温度得到土壤内部蒸发速率、显热通量、土层上下部显热通量差、潜在汽化热和显热贮藏量变化。与裸土相比,石子覆盖以后近表层显热贮藏量无明显变化,t检验3～9 mm、15～21 mm、27～33 mm p值分别为0.439、0.100和0.096,均大于0.05,显热通量减小,t检验3 mm、15 mm、27 mm p值分别为0、0、0.005,均小于0.05,土层上下部显热通量差明显减小,t检验3～9 mm、15～21 mm p值均为0<0.05,27～33 mm p值为0.059>0.05,潜在汽化热增加,t检验3～9 mm、15～21 mm、27～33 mm p值均为0<0.05,因此用于土壤蒸发的能量减小,致使土壤蒸发速率降低,t检验3～9 mm、15～21 mm p值均为0<0.05,27～33 mm p值均为0.100>0.05。土壤蒸发速率变化趋势与土壤显热通量差变化趋势一致:与裸土相比,石子覆盖以后土壤蒸发速率和土层上下部土壤显热通量差的峰值出现的时间滞后,3～9 mm、15～21 mm峰值出现的时间均滞后两天。因此石子覆盖以后土壤蒸发的变化主要表现在土壤蒸发速率减小且蒸发速率峰值出现时间滞后。展开更多
利用风洞模拟实验,研究了净风和挟沙风对砂田土壤风蚀的影响。结果表明:在净风吹蚀下,原状砂田的风蚀速率(0.37 g m-2min-1)分别是农田和荒地的1/4和1/5,风蚀速率随风速的增加呈指数函数递增,其中砂田的递增速度低于农田或荒地;翻耕后...利用风洞模拟实验,研究了净风和挟沙风对砂田土壤风蚀的影响。结果表明:在净风吹蚀下,原状砂田的风蚀速率(0.37 g m-2min-1)分别是农田和荒地的1/4和1/5,风蚀速率随风速的增加呈指数函数递增,其中砂田的递增速度低于农田或荒地;翻耕后的砂田在常见风速下的风蚀速率与农田和荒地相近(分别为1.67 g m-2 min-1、1.75 g m-2 min-1和1.83 g m-2 min-1),但在大风日则低于农田和荒地(分别为3.61 g m-2min-1、58.83 g m-2min-1和13.92 g m-2min-1)。挟砂田沙的风沙流吹蚀导致农田和翻耕砂田的风蚀速率增加,原状砂田则出现轻微的风积现象;挟农田土的风沙流吹蚀使原状砂田、翻耕砂田和荒地产生显著的风积,农田则出现更强烈的风蚀;挟沙风吹蚀下的风蚀(积)速率与风速的关系呈二次曲线函数。砂田的粗糙度明显高于农田(分别为0.023 cm和0.002 cm),且随着风速的增加,其间的差值越大;砂田和农田在不同风速条件下的风速廓线均可用指数函数表述。农田和荒地在压砂利用后,其抗风蚀和减尘性能显著增强。展开更多
基金provided by the Office of Agricultural Program, Chinese Academy of Sciences (kscx2-ewb-1-8)the National Natural Science Foundation of China (41171027)
文摘Gravel-sand mulch has been used for centuries to conserve water in the Loess Plateau of north- western China. In this study, we assessed the influence of long-term （1996-2012） gravel-sand mulching of cultiv- ated soils on total organic carbon （TOC）, light fraction organic carbon （LFOC）, microbial biomass carbon （MBC）, total organic nitrogen （TON）, particulate organic carbon （POC）, mineral-associated organic carbon （MOC）, perma- nganate-oxidizable carbon （KMnO4-C）, and non-KMnO4-C at 0-60 cm depths. Mulching durations were 7, 11 and 16 years, with a non-mulched control. Compared to the control, there was no significant and consistently positive effect of the mulch on TOC, POC, MOC, KMnO4-C and non-KMnO4-C before 11 years of mulching, and these organic C fractions generally decreased significantly by 16 years. LFOC, TON and MBC to at a 0-20 cm depth in- creased with increasing mulching duration until 11 years, and then these fractions decreased significantly between 11 and 16 years, reaching values comparable to or lower than those in the control. KMnO4-C was most strongly correlated with the labile soil C fractions. Our findings suggest that although gravel-sand mulch may conserve soil moisture, it may also lead to long-term decreases in labile soil organic C fractions and total organic N in the study area. The addition of manure or composted manure would be a good choice to reverse the soil deterioration that occurs after 11 years by increasing the inputs of organic matter.
文摘地表覆盖能够减少土壤蒸发,对土壤保水、保墒有重要意义。本文基于显热平衡原理,探究了石子覆盖对近表层土壤内部蒸发的影响。应用热脉冲技术测定的热参数和土壤温度得到土壤内部蒸发速率、显热通量、土层上下部显热通量差、潜在汽化热和显热贮藏量变化。与裸土相比,石子覆盖以后近表层显热贮藏量无明显变化,t检验3～9 mm、15～21 mm、27～33 mm p值分别为0.439、0.100和0.096,均大于0.05,显热通量减小,t检验3 mm、15 mm、27 mm p值分别为0、0、0.005,均小于0.05,土层上下部显热通量差明显减小,t检验3～9 mm、15～21 mm p值均为0<0.05,27～33 mm p值为0.059>0.05,潜在汽化热增加,t检验3～9 mm、15～21 mm、27～33 mm p值均为0<0.05,因此用于土壤蒸发的能量减小,致使土壤蒸发速率降低,t检验3～9 mm、15～21 mm p值均为0<0.05,27～33 mm p值均为0.100>0.05。土壤蒸发速率变化趋势与土壤显热通量差变化趋势一致:与裸土相比,石子覆盖以后土壤蒸发速率和土层上下部土壤显热通量差的峰值出现的时间滞后,3～9 mm、15～21 mm峰值出现的时间均滞后两天。因此石子覆盖以后土壤蒸发的变化主要表现在土壤蒸发速率减小且蒸发速率峰值出现时间滞后。
文摘利用风洞模拟实验,研究了净风和挟沙风对砂田土壤风蚀的影响。结果表明:在净风吹蚀下,原状砂田的风蚀速率(0.37 g m-2min-1)分别是农田和荒地的1/4和1/5,风蚀速率随风速的增加呈指数函数递增,其中砂田的递增速度低于农田或荒地;翻耕后的砂田在常见风速下的风蚀速率与农田和荒地相近(分别为1.67 g m-2 min-1、1.75 g m-2 min-1和1.83 g m-2 min-1),但在大风日则低于农田和荒地(分别为3.61 g m-2min-1、58.83 g m-2min-1和13.92 g m-2min-1)。挟砂田沙的风沙流吹蚀导致农田和翻耕砂田的风蚀速率增加,原状砂田则出现轻微的风积现象;挟农田土的风沙流吹蚀使原状砂田、翻耕砂田和荒地产生显著的风积,农田则出现更强烈的风蚀;挟沙风吹蚀下的风蚀(积)速率与风速的关系呈二次曲线函数。砂田的粗糙度明显高于农田(分别为0.023 cm和0.002 cm),且随着风速的增加,其间的差值越大;砂田和农田在不同风速条件下的风速廓线均可用指数函数表述。农田和荒地在压砂利用后,其抗风蚀和减尘性能显著增强。
