Soil functions (potential enzyme activity and nitrogen cycling rates) from manipulative experiment adding fertilizer and supplemental late-spring precipitation to a 50-ha northern California grassland underlain by a mosaic of serpentine and non-serpentine soils (November 2012-May 2013)

Experiment added fertilizer and supplemental late-spring precipitation to a 50-ha northern California grassland underlain by a mosaic of serpentine and non-serpentine soils. Measurements of soil functions were taken after three years of consistent treatment application.Contents are as follows:"plot.name": unique name for each of the 132 plots in the experiment"irrigation.line": code indicating which irrigation line carried the supplemental precipitation to the plot"soil.type": whether the plot was on harsh serpentine (Harshserp), lush serpentine (Lushserp), or non-serpentine (Nonserp) soil"treatment": C = control (no fertilizer or water added), F = fertilized (fertilizer added but no water added), W = watered (water added but no fertilizer added), FW = fertilized + watered (both fertilizer and water added)"watering": whether the plot was watered or unwatered"fertilization": whether the plot was fertilized or unfertilized"tpc.native": total proteolytic capacity with native substrate (no substrate added to soil) [mg N-AA / kg dry soil / day]; measured early May 2013"tpc.saturated": total proteolytic capacity with saturated substrate (saturating amount of casein added to soil) [mg N-AA / kg dry soil / day]; measured early May 2013"BG": potential activity of beta-1,4-glucosidase [mmol substrate cleaved / kg dry soil / hour]; measured early May 2013"NAG": potential activity of beta-N-acetylglucosaminidase [mmol substrate cleaved / kg dry soil / hour]; measured early May 2013"AP": potential activity of acid phosphatase [mmol substrate cleaved / kg dry soil / hour]; measured early May 2013"PPO": potential activity of polyphenol oxidase [mmol substrate cleaved / kg dry soil / hour]; measured early May 2013"PER": potential activity of peroxidase [mmol substrate cleaved / kg dry soil / hour]; measured early May 2013"fall.net.mineralization.rate": rate of net nitrogen mineralization during 7-day laboratory incubation at field moisture content [mg NH4-N + NO3-N / kg dry soil / day]; measured on soil samples collected early November 2012"fall.net.nitrification.rate": rate of net nitrification during 7-day laboratory incubation at field moisture content [mg NO3-N / kg dry soil / day]; measured on soil samples collected early November 2012"winter.net.mineralization.rate": rate of net nitrogen mineralization during 7-day laboratory incubation at field moisture content [mg NH4-N + NO3-N / kg dry soil / day]; measured on soil samples collected early February 2013"winter.net.nitrification.rate": rate of net nitrification during 7-day laboratory incubation at field moisture content [mg NO3-N / kg dry soil / day]; measured on soil samples collected early February 2013"earlyspring.net.mineralization.rate": rate of net nitrogen mineralization during 7-day laboratory incubation at field moisture content [mg NH4-N + NO3-N / kg dry soil / day]; measured on soil samples collected mid-March 2013"earlyspring.net.nitrification.rate": rate of net nitrification during 7-day laboratory incubation at field moisture content [mg NO3-N / kg dry soil / day]; measured on soil samples collected mid-March 2013"latespring.net.mineralization.rate": rate of net nitrogen mineralization during 7-day laboratory incubation at field moisture content [mg NH4-N + NO3-N / kg dry soil / day]; measured on soil samples collected late May 2013"latespring.net.nitrification.rate": rate of net nitrification during 7-day laboratory incubation at field moisture content [mg NO3-N / kg dry soil / day]; measured on soil samples collected late May 2013

本实验针对加利福尼亚北部一片50公顷的天然草地开展，该区域土壤呈蛇纹岩与非蛇纹岩镶嵌分布的格局，实验设置了施肥与春末补充降水两种处理，持续施加三年后对土壤功能进行测定。实验共包含132个样地，各变量说明如下：
plot.name（样地名称）：实验中132个样地的唯一标识
irrigation.line（灌溉管线编号）：用于标识为对应样地输送补充降水的灌溉管线代码
soil.type（土壤类型）：分为三类，分别为严酷型蛇纹岩土（Harshserp）、丰沃型蛇纹岩土（Lushserp）与非蛇纹岩土（Nonserp）
treatment（处理组）：C为对照组（不施加肥料与水分）、F为施肥组（施加肥料但不补水）、W为补水组（补水但不施肥）、FW为施肥补水组（同时施加肥料与水分）
watering（灌溉状态）：标识该样地是否接受补水处理
fertilization（施肥状态）：标识该样地是否接受施肥处理
tpc.native（天然底物总蛋白水解能力）：以无外源底物添加的土壤为测试对象的总蛋白水解能力，单位为[mg N-AA / kg干土 / 天]，于2013年5月初测定
tpc.saturated（饱和底物总蛋白水解能力）：以添加饱和浓度酪蛋白的土壤为测试对象的总蛋白水解能力，单位为[mg N-AA / kg干土 / 天]，于2013年5月初测定
BG（β-1,4-葡萄糖苷酶潜在活性）：单位为[mmol底物裂解 / kg干土 / 小时]，于2013年5月初测定
NAG（β-N-乙酰氨基葡萄糖苷酶潜在活性）：单位为[mmol底物裂解 / kg干土 / 小时]，于2013年5月初测定
AP（酸性磷酸酶潜在活性）：单位为[mmol底物裂解 / kg干土 / 小时]，于2013年5月初测定
PPO（多酚氧化酶潜在活性）：单位为[mmol底物裂解 / kg干土 / 小时]，于2013年5月初测定
PER（过氧化物酶潜在活性）：单位为[mmol底物裂解 / kg干土 / 小时]，于2013年5月初测定
fall.net.mineralization.rate（秋季净氮矿化速率）：指在田间持水量条件下进行7天实验室培养时的净氮矿化速率，单位为[mg NH4-N + NO3-N / kg干土 / 天]，基于2012年11月初采集的土样测定
fall.net.nitrification.rate（秋季净硝化速率）：指在田间持水量条件下进行7天实验室培养时的净硝化速率，单位为[mg NO3-N / kg干土 / 天]，基于2012年11月初采集的土样测定
winter.net.mineralization.rate（冬季净氮矿化速率）：指在田间持水量条件下进行7天实验室培养时的净氮矿化速率，单位为[mg NH4-N + NO3-N / kg干土 / 天]，基于2013年2月初采集的土样测定
winter.net.nitrification.rate（冬季净硝化速率）：指在田间持水量条件下进行7天实验室培养时的净硝化速率，单位为[mg NO3-N / kg干土 / 天]，基于2013年2月初采集的土样测定
earlyspring.net.mineralization.rate（早春净氮矿化速率）：指在田间持水量条件下进行7天实验室培养时的净氮矿化速率，单位为[mg NH4-N + NO3-N / kg干土 / 天]，基于2013年3月中旬采集的土样测定
earlyspring.net.nitrification.rate（早春净硝化速率）：指在田间持水量条件下进行7天实验室培养时的净硝化速率，单位为[mg NO3-N / kg干土 / 天]，基于2013年3月中旬采集的土样测定
latespring.net.mineralization.rate（晚春净氮矿化速率）：指在田间持水量条件下进行7天实验室培养时的净氮矿化速率，单位为[mg NH4-N + NO3-N / kg干土 / 天]，基于2013年5月下旬采集的土样测定
latespring.net.nitrification.rate（晚春净硝化速率）：指在田间持水量条件下进行7天实验室培养时的净硝化速率，单位为[mg NO3-N / kg干土 / 天]，基于2013年5月下旬采集的土样测定