Clever Cover Cropping : Litter trait diversities and elemental flows

Abstract

Table 2.1Soil mineral N (kg N-NO3 + N-NO2 + N-NH4 ha -1 ). Different lowercase letters indicate significant differences between cover crop treatments for each sample date (n = 5; * p < 0.05, ** p < 0.01, *** p < 0.001). Radish (R), vetch (V), oat (O), their 2-and 3-species mixtures and a fallow (Fal).

Proefopzet, onderzoeksvragen en methodologie van de PPS Groenbemesters : Groenbemesters, de onmisbare schakel voor robuuste kringlooplandbouw

“…In verschillende proeven zijn de effecten van groenbemesters op nutriëntoverdracht, -verliezen en -efficiëntie onderzocht (e.g. Vos & van der Putten, 2001;Vos & van der Putten, 2004;Premroy et al, 2014;Plaza-Bonilla et al, 2015;Drost et al, 2020;Porre, 2020;van Geel et al, 2010;van Geel et al, 2012;van Geel et al, 2023). Kennis over het effect van zaaimoment, inwerkmethode, mineralisatie en op het volggewas is beperkt.…”

Road verge cuttings as organic amendment on arable fields : Mechanisms, benefits and risks

“…For the field experiment of chapter 2, I do not have the data of g C in the silt and clay fraction/kg soil and thus cannot quantify the level of C saturation. However, to get an idea of the potential C saturation level, I looked at studies that used a comparable soil type as for example in the study of Porre et al (2020). Porre et al (2020) worked in an arable cropping system with soil with a high similarity to the soils used in my thesis in terms of clay, silt, sand and SOM percentage, 2 %, 12 %, 86 % and 3.1 % respectively, and in terms of geographic and climatic origin, and showed that the soil was indeed saturated in the level of C that was bound to mineral surfaces.…”

“…However, to get an idea of the potential C saturation level, I looked at studies that used a comparable soil type as for example in the study of Porre et al (2020). Porre et al (2020) worked in an arable cropping system with soil with a high similarity to the soils used in my thesis in terms of clay, silt, sand and SOM percentage, 2 %, 12 %, 86 % and 3.1 % respectively, and in terms of geographic and climatic origin, and showed that the soil was indeed saturated in the level of C that was bound to mineral surfaces. Therefore, it is possible that the soils in my experiments are already reaching C saturation in the mineral associated SOM.…”

“…The results align since chapter 3 proved that leaching only occurs when no plants are present and after intense rainfalls and chapter 2 shows no sign of leaching probably because the soil was not left bare for extended periods and no heavy rainfall periods occurred during period with bare soil. Growing plants is a well-known method to prevent N leaching (Porre, 2020;Thapa et al, 2018) and underlies Dutch regulations obliging farmers to grow cover crops in certain crop rotations. Despite the good results on N leaching in my thesis, caution still needs to be taken when applying the organic amendment at a different time in the crop cycle since the timing in our field experiment did not result in N leaching but a different timing of application and therefore N mineralization during a fallow or wet period will increase the change of N leaching (Pang and Letey, 2000).…”