Abstract

Increasing soil microbial respiration is thought to increase the soil organic matter (SOM) decomposition and hence the soil fertility. It was hypothesized that whether N or C rich drivers enhance the SOM decomposition if amended with farmyard manure (FYM). Thus, an experiment was designed using four key drivers i.e. 1) Control (No-amendment), 2) Min-N (urea @ 30 kg N ha⁻¹ as N rich amendment), 3) HA (Humic acid @ of 2.5 kg ha⁻¹ as C rich amendment) and 4) EM (effective microbes @ 200 L Mg⁻¹ FYM as microbial solution). These four key drivers were mixed with different levels of FYM i.e. (0, 5, 10, 15 and 20 Mg ha⁻¹) and were added to 100 g soil in vials. These vials were incubated for 90 days at 25 °C and destructive periodic sampling were made after 1, 3, 15, 30, 45 and 90 days. The mineral N availability was 3 times higher with 20 Mg FYM ha⁻¹ than No-FYM treatment. The degrading order of soil organic carbon (EM > HA > Min-N > control) resulted in soil respiration of the same order. However, the degrading order of TN (EM > Min-N > HA > control) caused positive changes for mineral N availability with EM (31.3‰ day⁻¹) and negative changes with Min-N (257‰ day⁻¹). The mineral N availability last for 45 days with EM and 30 days for HA. According to principle component analysis, EM increased MBC, mineral N, soil respiration and has positive effects for PC-1 (63%) whereas Min-N increased the SOC and TN and has negative effects both for PC1 (63%) and PC-2 (22%). In conclusion, the SOM decomposition increased by Min-N (23%), EM (42%), HA (32%) with increasing FYM level from 0 Mg ha⁻¹ to 5, 10, and 15 Mg ha⁻¹, respectively. Thus, for C rich driver more FYM should be used than N rich driver for higher SOM decomposition.

• Highlights

• The effect of C and N rich amendment on SOM decomposition was studied.

• No direct addition of C and N drivers on SOM decomposition is yet documented.

• Increasing manure increased SOM decomposition and hence the soil respiration and mineral N.

• The increased decomposition of SOM needs more FYM with C rich than N rich driver.

摘要

人们认为增加土壤微生物的呼吸作用会增加土壤有机质（SOM）的分解，从而增加土壤肥力。假设如果使用农家肥（FYM）进行修正，则富含N或C的驱动因子是否会增强SOM分解。因此，使用四个关键驱动因素设计了一个实验，即1）控制（无修正），2）Min-N（尿素@ 30 kg N ha ^-1作为富氮修正剂），3）HA（腐殖酸@ 2.5 kg ha ^-1为富碳修正物）和4）EM（有效微生物@ 200 L Mg ^-1 FYM作为微生物溶液）。这四个主要驱动因素与不同水平的FYM混合在一起，即（0、5、10、15和20 Mg ha ^-1）并加入小瓶中100 g的土壤中。这些小瓶在25°C下孵育90天，然后在1、3、15、30、45和90天后进行破坏性的定期采样。FYM ha ^-1为20 Mg时，矿物N的利用率比No-FYM处理高3倍。土壤有机碳的降解顺序（EM> HA> Min-N>对照）导致相同程度的土壤呼吸。但是，TN的降级顺序（EM> Min-N> HA>对照）导致EM（31.3‰day ^-1）的矿物氮有效性正变化，而Min-N（257‰day ^-1）的负变化。）。矿物氮的有效期持续EM为45天，HA为30天。根据主成分分析，EM增加MBC，矿质N，土壤呼吸并对PC-1产生积极影响（63％），而Min-N增加SOC和TN，对PC1（63％）和PC-均产生负面影响2（22％）。总之，随着FYM水平从0 Mg ha ^-1增加到5、10和15 Mg ha ^-1，SOM分解分别增加了Min-N（23％），EM（42％），HA（32％）。。因此，对于富C驱动程序，应使用比富N驱动程序更多的FYM，以实现更高的SOM分解。

• 强调

• 研究了富含C和N的修饰物对SOM分解的影响。

• 尚无关于在SOM分解上直接添加C和N驱动程序的记录。

• 粪肥增加会增加SOM分解，从而增加土壤呼吸和矿质氮。

• SOM分解的增加需要富C的FYM比富N的驱动器更多。