Responses of spring-seeded cover crop roots by herbicide residues and short-term influence in soil aggregate stability and N cycling

2018 ◽  
Vol 98 (5) ◽  
pp. 990-1004 ◽  
Author(s):  
María A. Rojas ◽  
Laura L. Van Eerd ◽  
Ivan P. O’Halloran ◽  
Peter H. Sikkema ◽  
Darren E. Robinson

Cover crop (CC) prevalence between cash crop systems is contributing to long-term sustainable crop production systems. However, herbicide residue impact on CC root growth and its subsequent effect on soil aggregation and fertility are unknown. An untreated control plus preemergence (PRE) application of saflufenacil (at 67 and 134 g a.i. ha−1)/dimethenamid-P (at 668 and 1336 g a.i. ha−1) as well as S-metolachlor (at 1600 and 3200 g a.i. ha−1)/atrazine (at 1280 and 2560 g a.i. ha−1) + mesotrione at 140 and 280 g a.i. ha−1to sweet corn (Zea mays L. var. rugosa Bonaf.) and imazethapyr (100 and 200 g a.i. ha−1) to pea (Pisum sativum L.) were made in spring 2011 and spring 2012. One year later, ryegrass (Lolium multiflorum Lam.), buckwheat (Fagopyrum esculentum Moench), sorghum–sudangrass [Sorghum bicolor (L.) Moench × S. bicolor var. sudanese (L.)], and spring wheat (Triticum aestivum L.) were seeded. Root biomass and N content, wet aggregate stability (WAS), and aggregate size plus soil mineral N (SMN) were determined. Buckwheat root biomass declined in all herbicide treatments but root N declined in imazethapyr and S-metolachlor/atrazine + mesotrione at the 2× and 1× rates, respectively. Ryegrass root biomass decreased in S-metolachlor/atrazine + mesotrione but root N content declined only at the 2× rate. Sorghum–sudangrass and spring wheat roots decreased in imazethapyr and S-metolachlor/atrazine + mesotrione at the 2× rate, respectively. Despite the impact of herbicide residues on roots, differences in aggregate size, WAS, and SMN were not detected. Findings from this study add knowledge on herbicide residue effect on CC root growth and provide useful CC seeding guidelines for growers.

Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 891 ◽  
Author(s):  
AJ Gijsman

An area of native savanna on an Oxisol in the Eastern Plains of Colombia was opened and sown to various rotations of grass or grass-legume pasture with rice. After 4.5 years, the soil was sampled for studying the effect of land conversion on soil aggregation and on the distribution of total and particulate soil organic matter across the aggregate size classes. The size distribution of undisturbed aggregates did not vary among treatments. Five different methods were used to measure wet aggregate stability (WAS). The choice of method affected the WAS average across treatments as well as the differences among treatments. The only consistent observation was the lower WAS under monocropped rice compared with the other treatments. Inclusion of a legume in a pasture hardly affected aggregate stability. In contrast to the WAS measurements, which were carried out with soil aggregates of 1-2 mm, wet sieving of whole-soil samples revealed additional differences among treatments: large macroaggregates (>2 mm) proved less stable under those treatments that involved soil disturbance through ploughing and harvesting. Total soil C and N content did not vary among treatments, despite considerable differences in plant production levels. The C concentration, but not the N concentration, declined with decreasing aggregate size. The distribution of whole-soil C and N content across aggregate size classes depended more on the amount of soil in a certain size class than on the size class's C or N concentration. Those treatments that involved frequent soil disturbance had a smaller fraction of large macroaggregates (>2 mm) and, as a consequence, less C and N in the large macroaggregate fraction. The particulate organic matter (POM) fraction accounted for only 6.2-8.5% of total soil carbon. The small size of this pool makes it unlikely that POM can serve in these Oxisols for estimating the amount of soil organic matter with medium turnover rate, as suggested by others.


1992 ◽  
Vol 6 (2) ◽  
pp. 252-261 ◽  
Author(s):  
William W. Donald

Several sequences of POST herbicides applied each year in fall alone, in spring alone, or both in fall and again in spring controlled Canada thistle stands in spring wheat by severely decreasing root biomass and the numbers of adventitious root buds to a depth of 50 cm over four years. These treatments included dicamba applied at 1.7 or 2.2 kg ae ha–1for the first two successive falls followed in wheat by either chlorsulfuron at 30 g ai ha–1plus nonionic surfactant, MCPA plus bromoxynil at 280 plus 280 g ha–1, or 2,4-D amine at 560 g ha–1applied annually for each of four consecutive years from the start. Chlorsulfuron at 30 g ha–1applied alone in spring for each of four years also reduced and prevented Canada thistle root growth as effectively as a sequence of fall-applied dicamba followed by spring-applied chlorsulfuron in spring wheat.


2000 ◽  
Vol 80 (2) ◽  
pp. 363-366 ◽  
Author(s):  
B. R. Ball-Coelho ◽  
R. C. Roy ◽  
C. J. Swanton

In corn (Zea mays L.) – soybean [Glycine max (L.) Merr.] – winter wheat (Triticum aestivum L.) rotations cultivated in sandy soil under three tillage systems, with and without cover cropping, the soil wind-erodible fraction (<0.85 mm) ranged from 78 to 96%. Proportion and wet-aggregate stability (WAS) of the 0.85- to 5.7-mm fraction both ranked no-till (8.1% of total soil weight and 49% water-stable) > chisel plow (6.7 and 39%) > conventional plow (5.3 and 35%). Cover cropping had little effect on dry aggregate size distribution or WAS. Key words: Zea mays, Secalecereale, soil structure, aggregate stability, cover crop, tillage


Agriculture ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 441
Author(s):  
Hans J. Kandel ◽  
Dulan P. Samarappuli ◽  
Kory L. Johnson ◽  
Marisol T. Berti

Adoption of cover crop interseeding in the northwestern Corn Belt in the USA is limited due to inadequate fall moisture for establishment, short growing season, additional costs, and need for adapted winter-hardy species. This study evaluated three cover crop treatments—no cover crop, winter rye (Secale cereale L.), and winter camelina (Camelina sativa (L.) Crantz)—which were interseeded at the R6 soybean growth stage, using two different soybean (Glycine max (L.) Merr.) maturity groups (0.5 vs. 0.9) and two row spacings (30.5 vs. 61 cm). The objective was to evaluate these treatments on cover crop biomass, soil cover, plant density, and soybean yield. Spring wheat (Triticum aestivum L.) grain yield was also measured the following year. The early-maturing soybean cultivar (0.5 maturity) resulted in increased cover crop biomass and soil cover, with winter rye outperforming winter camelina. However, the early-maturing soybean yielded 2308 kg·ha−1, significantly less compared with the later maturing cultivar (2445 kg·ha−1). Narrow row spacing had higher soybean yield, but row spacing did not affect cover crop growth. Spring wheat should not follow winter rye if rye is terminated right before seeding the wheat. However, wheat planted after winter camelina was no different than when no cover crop was interseeded in soybean. Interseeding cover crops into established soybean is possible, however, cover crop biomass accumulation and soil cover are limited.


Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 153 ◽  
Author(s):  
AJ Gijsman ◽  
RJ Thomas

This study evaluated soil aggregate size distribution and stability of an Oxisol under improved grass-only or grass-legume pastures, established in previously native savanna. Three grass-legume combinations were included at various stocking rates. In all treatments and soil layers, soils were well aggregated, having more than 90% of their weight in macroaggregates (>250 �m). The addition of legumes to pastures did not affect the soil aggregate size distribution, although aggregates showed somewhat more stability against slaking. An increase in stocking rate negatively affected both average aggregate size and aggregate stability. Aggregates showed little or no dispersion of clay particles in any treatment. A positive correlation was found between wet aggregate stability and hot-water extractable carbohydrate concentration, supporting the hypothesis that these carbohydrates equate with plant-derived or microbial polysaccharides which glue soil aggregates together. It is suggested that determination of hot-water extractable carbohydrates may serve as a useful indicator of small differences in aggregate stability, even when these differences are not evident in the stability measurement itself.


2020 ◽  
Author(s):  
Dan-Dan Li ◽  
Hong-Wei Nan ◽  
Chun-Zhang Zhao ◽  
Chun-Ying Yin ◽  
Qing Liu

Abstract Aims Competition, temperature, and nutrient are the most important determinants of tree growth in the cold climate on the eastern Tibetan Plateau. Although many studies have reported their individual effects on tree growth, little is known about how the interactions of competition with fertilization and temperature affect root growth. We aim to test whether climate warming and fertilization promote competition and to explore the functional strategies of Picea asperata in response to the interactions of these factors. Methods We conducted a paired experiment including competition and non-competition treatments under elevated temperature (ET) and fertilization. We measured root traits, including the root tip number over the root surface (RTRS), the root branching events over the root surface (RBRS), the specific root length (SRL), the specific root area (SRA), the total fine root length and area (RL and RA), the root tips (RT) and root branching events (RB). These root traits are considered to be indicators of plant resource uptake capacity and root growth. The root biomass and the nutrient concentrations in the roots were also determined. Important Findings The results indicated that ET, fertilization and competition individually enhanced the nitrogen (N) and potassium (K) concentrations in fine roots, but they did not affect fine root biomass or root traits, including RL, RT, RA and RB. However, both temperature and fertilization, as well as their interaction, interacting with competition increased RL, RA, RT, RB, and nutrient uptake. In addition, the SRL, SRA, RTRS and RBRS decreased under fertilization, the interaction between temperature and competition decreased SRL and SRA, while the other parameters were not affected by temperature or competition. These results indicate that Picea asperata maintains a conservative nutrient strategy in response to competition, climate warming, fertilization, and their interactions. Our results improve our understanding of the physiological and ecological adaptability of trees to global change.


2019 ◽  
Author(s):  
Fayong Li ◽  
Xinqiang Liang ◽  
Hua Li ◽  
Yingbin Jin ◽  
Junwei Jin ◽  
...  

Abstract Background Colloid-facilitated phosphorus (P) transport is a recognized important pathway for soil P loss in agricultural systems, but limited information is available on the soil aggregate-associated colloidal P. To elucidate the effects of aggregate size on the loss potential of colloidal P (P coll ) in agricultural systems, soils (0-20 cm depth) from six land use types were sampled in Zhejiang province in the Yangtz river delta region, China. The aggregate size fractions (2–8 mm, 0.26–2 mm, 0.053–0.26 mm and <0.053 mm) separated by wet-sieving method were analyzed.Results Results showed that the 0.26–2 mm small macroaggregates had the highest total P (TP) content. For acidic soils, the highest P coll content was also found in the 0.26–2 mm aggregate size, while the lowest was found in the <0.053 mm (silt+clay)-sized particles, the opposite of that found in alkaline soils. Paddy soils contained less P coll than other land use types. The P coll in total dissolved P (TDP) was dominated by <0.053 mm (silt+clay)-sized particles. Aggregate size did strongly influence the loss potential of P coll in paddy soils, where P coll contributed up to 83% TDP in the silt+clay sized particles. The P coll content was positively correlated with TP, Al, Fe and mean weight diameter (MWD). Aggregate associated total carbon (TC), total nitrogen (TN), C/P, and C/N had significant, but negative effects on the contribution of P coll to potential soil P losses. The P coll content of the aggregates was controlled by aggregate associated TP and Al content as well as soil pH value, with P coll loss potential from aggregates being controlled by its organic matter content.Conclusion Therefore, we conclude that management practices that increase soil aggregate stability or its organic carbon content will limit P coll loss from agricultural systems.


Author(s):  
Maria Theresia Sri Budiastuti ◽  
Djoko Purnomo ◽  
Supriyono Supriyono ◽  
Bambang Pujiasmanto ◽  
Desy Setyaningrum

<p class="Default"><em>Indigofera tinctoria</em> is a legume that is cultivated as a source of natural indigo dyes. As a legume, <em>Indigofera tinctoria</em> is capable of symbiosis with soil microbes. This study evaluates the effects of light intensity and microbial inoculation on root growth and nodulation. The study used a complete randomized block design with a split-plot pattern. Light intensity was the main plot with four levels of light intensity 100%, 50%, 25%, and 10%. Microbial inoculation was a subplot with four levels without inoculation, mycorrhizae inoculation, rhizobium inoculation, and double inoculation with both mycorrhizae and rhizobium. The results obtained show that light intensity and microbial inoculation affected root length, root fresh weight, root biomass, and the number of nodules. 50% light intensity was optimum for root length, while 100% light intensity was optimum for root fresh weight, root biomass, and a number of nodules. Root growth and nodulation were further increased with double inoculation. The combination of light intensity and microbial inoculation affected root biomass and nodulation. The combination of 100% light intensity and double inoculation resulted in the highest root biomass and nodule numbers. Mycorrhizae and rhizobium have a synergistic relationship to nodulation and root growth. Double inoculation with mycorrhizae and rhizobium efficiently increased root biomass and the number of nodules under low or high light intensity.</p>


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