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Early adoption of no-till mitigates soil organic carbon and nitrogen losses due to land use change
Soil and Tillage Research ( IF 6.5 ) Pub Date : 2020-07-10 , DOI: 10.1016/j.still.2020.104728
Camila R. Wuaden , Rodrigo S. Nicoloso , Evandro C. Barros , Roberto A. Grave

Conversion of grasslands to agriculture has promoted land degradation and losses of soil organic carbon (SOC). Early adoption of no-till (NT) and use of organic fertilizers could mitigate SOC losses in response to minimum soil disturbance and increased carbon (C) inputs. To test this hypothesis, we assessed changes on soil C and nitrogen (N) pools in a Nitisol under natural grassland vegetation from Southern Brazil. The grassland was converted to agriculture in 2012 with a double-cropping system of maize (Zea mays L.) and black oats (Avena strigosa Scherb.). The experiment had split-plots replicated in four randomized blocks. Conventional tillage (CT) and NT systems were tested in the main plots (10 × 25 m, LxW). Maize was amended with 140 kg N-total ha−1 from different N sources in the subplots (10 × 5 m): urea (UR), pig slurry (PS), digested pig slurry (DS), and composted pig slurry (CS), besides a control treatment without fertilization (CTR). Soil was sampled in 2012 and 2017 to assess short-term changes (5 years) on total organic C (TOC) and N (TN) stocks in the 0−60 cm depth as well on the particulate and mineral associated C and N pools in the 0−30 cm soil layer. We also assessed C and N contents within water-stable aggregates (WSA) in the 0−5 cm soil layer. Soils under CT have lost 9 % of TOC and 21 % of TN (11.5 and 2.6 Mg ha−1, respectively) from the 0−60 cm layer as compared with original stocks under the grassland. No-till soils accumulated TOC at surface layers and mitigated TOC and TN losses by respective 82 and 34 % when compared with the grassland in the 0−60 cm layer. No-till increased particulate C and N fractions compensating losses on the respective mineral associated fractions. In contrast, depletion of mineral associated fractions accounted for most of total C and N stocks losses under CT. No-till soils had nearly doubled the mass of large macroaggregates and tripled the C and N contents within this WSA fraction as compared with CT. The use of CS augmented C and N contents within large macroaggregates by respective 35 and 40 % in comparison with UR and by 72 and 86 %, respectively, if compared with the CTR. Early adoption of NT can mitigate TOC losses following conversion of grasslands to agriculture. The association of NT with CS augmented C and N stabilization within large macroaggregates, improved soil quality and may contribute with SOC accrual in NT soils.



中文翻译:

尽早采用免耕措施可减轻因土地用途变化而造成的土壤有机碳和氮的损失

草原向农业的转化促进了土地退化和土壤有机碳(SOC)的流失。尽早采用免耕(NT)和使用有机肥料可以减轻SOC的损失,以减少土壤干扰并增加碳(C)的投入。为了检验该假设,我们评估了巴西南部天然草原植被下尼蒂索尔土壤碳和氮(N)库的变化。草原于2012年转化为农业,其中包括玉米(Zea mays L.)和黑燕麦(Avena strigosa Scherb。)的双作系统。该实验在四个随机区组中重复了裂口图。在主要地块(10×25 m,长x宽)上测试了常规耕作(CT)和NT系统。玉米的氮素总量调整为140 kg ha -1来自亚地段(10×5 m)中不同N来源的尿素(UR),猪粪(PS),消化猪粪(DS)和堆肥猪粪(CS),以及不施肥的对照处理(CTR)。在2012年和2017年对土壤进行了采样,以评估0-60厘米深度的土壤总有机碳(TOC)和氮(TN)储量以及颗粒和矿物相关的碳和氮库的短期变化(5年) 0-30厘米土壤层。我们还评估了0-5厘米土壤层中水稳性团聚体(WSA)中的碳和氮含量。CT下的土壤损失了9%的TOC和21%的TN(11.5和2.6 Mg ha -1分别来自0-60厘米的层,与草原下的原始种群相比。与0-60 cm层的草地相比,免耕土壤在表层积累了TOC,并分别减少了82%和34%的TOC和TN损失。免耕增加的颗粒C和N馏分补偿了与矿物相关的馏分的损失。相反,在CT下,与矿物有关的馏分的消耗占总C和N储量损失的大部分。与CT相比,免耕土壤在该WSA馏分中的大型大型骨料的质量几乎增加了一倍,并且C和N含量增加了三倍。CS的使用使大型宏聚集体中的C和N含量与UR相比分别增加了35%和40%,与CTR相比分别增加了72%和86%。早期采用NT可以减轻草地转化为农业后TOC的损失。NT与CS的结合增强了大型大型骨料中的C和N稳定性,改善了土壤质量,并可能有助于NT土壤中的SOC累积。

更新日期:2020-07-10
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