scholarly journals Utilisation of Cover Crops: Implications for Conservation Agriculture Systems in a Mediterranean Climate Region of South Africa

Author(s):  
Ernst H. Smit ◽  
Johann A. Strauss ◽  
Pieter Andreas Swanepoel

Abstract PurposeCover crops can provide multiple agroecosystem services to crops produced in conservation agriculture systems. South African grain producers in the Mediterranean climate region are reluctant to integrate cover crops in rainfed systems since cover crops replace cash crops leading to financial losses. Using cover crops as fodder can help cover input costs, while providing a range of advantageous services to the cropping system. The aim of this study was to investigate how cover crop mixtures and the utilisation of cover crops affect soil quality, the quality and quantity of the mulch as well as wheat (Triticum aestivum L.) produced in the subsequent year.MethodsA two-year study was conducted in the Western Cape Province of South Africa. In Year 1, diverse legume and cereal-based cover crop mixtures were partially grazed, cut and material removed for haymaking, or left unutilised as a mulch. In Year 2, spring wheat (Triticum aestivum L.) was planted to investigate the effects of cover crop mixtures and utilisation method on subsequent spring wheat yield. ResultsCover crops used as hay or for grazing did not affect (P < 0.05) grain yield of wheat that followed in rotation. Legume-based cover crop mixtures increased (P < 0.05) wheat grain protein content regardless of utilisation method. Soil quality and nitrogen content improved (P < 0.05) when cover crops were grazed. ConclusionsCover cropping can be used by South African grain producers as an important agronomic tactic to improve system productivity and support sustainable intensification of rainfed cropping systems.

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.


2011 ◽  
Vol 26 (4) ◽  
pp. 342-353 ◽  
Author(s):  
David Bruce Lewis ◽  
Jason P. Kaye ◽  
Randa Jabbour ◽  
Mary E. Barbercheck

AbstractWeed management is one of the primary challenges for producers transitioning from conventional to organic agriculture. Tillage and the use of cover crops are two weed control tactics available to farmers transitioning to organic management, but little is known about their interactive effects on soil quality during the transition period. We investigated the response of soils to tillage and initial cover crop during the 3-year transition to organic in a cover crop–soybean (Glycine max)–maize (Zea mays) rotation in the Mid-Atlantic region of the USA. The tillage treatment contrasted full, inversion tillage with moldboard plowing (FT) versus reduced tillage with chisel plowing (RT). The cover crop treatment contrasted annual versus mostly perennial species during the first year of the rotation. The experiment was initiated twice (Start 1 and Start 2), in consecutive years in adjacent fields. By the end of the experiment, labile carbon, electrical conductivity, pH and soil moisture were all greater under RT than under FT in both starts. Soil organic matter and several other soil attributes were greater under RT than under FT in Start 1, but not in Start 2, perhaps owing to differences between starts in initial field conditions and realized weather. Soil attributes did not differ between the two cover crop treatments. Combining our soils results with agronomic and economic analyses on these plots suggests that using RT during the organic transition can increase soil quality without compromising yield and profitability.


2010 ◽  
Vol 46 (3) ◽  
pp. 309-325 ◽  
Author(s):  
C. THIERFELDER ◽  
P. C. WALL

SUMMARYConservation agriculture (CA) systems are based on minimal soil disturbance, crop residue retention and crop rotation. Although the capacity of rotations to break pest and disease cycles is generally recognized, other benefits of crop rotations in CA systems are seldom acknowledged and little understood. We monitored different conventional and CA cropping systems over the period from 2005 to 2009 in a multi-seasonal trial in Monze, southern Zambia. Both monocropped maize and different maize rotations including cotton and the green manure cover crop sunnhemp (Crotalaria juncea) were compared under CA conditions, with the aim of elucidating the effects of crop rotations on soil quality, soil moisture relations and maize productivity. Infiltration, a sensitive indicator of soil quality, was significantly lower on conventionally ploughed plots in all cropping seasons compared to CA plots. Higher water infiltration rate led to greater soil moisture content in CA maize treatments seeded after cotton. Earthworm populations, total carbon and aggregate stability were also significantly higher on CA plots. Improvements in soil quality resulted in higher rainfall use efficiency and higher maize grain yield on CA plots especially those in a two- or three-year rotation. In the 2007/08 and 2008/2009 season, highest yields were obtained from direct-seeded maize after sunnhemp, which yielded 74% and 136% more than maize in the conventionally ploughed control treatment with a continuous maize crop. Even in a two-year rotation (maize-cotton), without a legume green manure cover crop, 47% and 38% higher maize yields were recorded compared to maize in the conventionally ploughed control in the two years, respectively. This suggests that there are positive effects from crop rotations even in the absence of disease and pest problems. The overall profitability of each system will, however, depend on markets and prices, which will guide the farmer's decision on which, if any, rotation to choose.


2022 ◽  
pp. 416-430
Author(s):  
Hendrik J. Smith ◽  
Gerhardus Trytsman ◽  
Andre A. Nel

Abstract A project under the Farmer Innovation Programme (FIP) that aimed to adapt Conservation Agriculture (CA) among grain farmers in South Africa was implemented in a commercial farming area of the North West Province. The following on-farm, collaborative-managed trials produced key findings concerning: (i) plant population densities (high versus low) under CA; (ii) conventional crop systems versus CA crop systems; (iii) the testing and screening of cover crops; (iv) green fallow systems for soil restoration; and (v) livestock integration. Key results from these trials were that the yield of maize was significantly higher under high-density no-till (NT) systems compared to the normal NT systems. The yield of maize in local conventional systems was lower than the yield in NT systems tested on three farmer-managed trials. The screening trial assisted in testing and learning the suitability and the different attributes of a range of cover crops in that area. Cover crop mixtures used as a green fallow system with livestock showed that CA can facilitate the successful restoration of degraded soil.


Crop Science ◽  
2015 ◽  
Vol 55 (4) ◽  
pp. 1791-1805 ◽  
Author(s):  
Blessing Mhlanga ◽  
Stephanie Cheesman ◽  
Barbara Maasdorp ◽  
Walter Mupangwa ◽  
Christian Thierfelder

Author(s):  
Mandla Dlamini ◽  
George Chirima ◽  
Nebo Jovanovic ◽  
Elhadi Adam

This study investigated the impacts of cultivation on water and soil quality in the lower uMfolozi floodplain system in KwaZulu-Natal province, South Africa. We did this by assessing seasonal variations in purposefully selected water and soil properties in these two land-use systems. The observed values were statistically analysed by performing Student’s paired t-tests to determine seasonal trends in these variables. Results revealed significant seasonal differences in chloride and sodium concentrations and electrical conductivity (EC) and the sodium adsorption ratio (SAR) with cultivated sites exhibiting higher values. Most of the analyzed chemical parameters were within acceptable limits specified by the South African agricultural-water-quality (SAWQ) water quality guidelines for irrigation except for sodium adsorption ratio (SAR), chloride, sodium and EC. EC, pH and nitrate content which were higher than the specified SAWQ limits in cultivated sites. Quantities of glyphosate, ametryn and imidacloprid could not be measured because they were below detectable limits. The study concludes that most water quality parameters met SAWQ’s standards. These results argue for concerted efforts to systematically monitor water and soil quality characteristics in this environment to enhance sustainability by providing timely information for management purposes.


Author(s):  
Maryse Bourgault ◽  
Samuel A. Wyffels ◽  
Julia M. Dafoe ◽  
Peggy F. Lamb ◽  
Darrin L. Boss

Abstract The introduction of cover crops as fallow replacement in the traditional cereal-based cropping system of the Northern Great Plains has the potential to decrease soil erosion, increase water infiltration, reduce weed pressure and improve soil health. However, there are concerns this might come at the cost of reduced production in the subsequent wheat crop due to soil water use by the cover crops. To determine this risk, a phased 2-year rotation of 15 different cover crop mixtures and winter wheat/spring wheat was established at the Northern Agricultural Research Center near Havre, MT from 2012 to 2020, or four rotation cycles. Controls included fallow–wheat and barley–wheat sequences. Cover crops and barley were terminated early July by haying, grazing or herbicide application. Yields were significantly decreased in wheat following cover crops in 3 out of 8 years, up to maximum of 1.4 t ha−1 (or 60%) for winter wheat following cool-season cover crop mixtures. However, cover crops also unexpectedly increased following wheat yields in 2018, possibly due in part to residual fertilizer. Within cool-, mid- and warm-season cover crop groups, individual mixtures did not show significant differences impact on following grain yields. Similarly, cover crop termination methods had no impact on spring or winter wheat grain yields in any of the 8 years considered. Wheat grain protein concentration was not affected by cover crop mixtures or termination treatments but was decreased in winter wheat following barley. Differences in soil water content across cover crop groups were only evident at the beginning of the third cycle in one field, but important reductions were observed below 15 cm in the last rotation cycle. In-season rainfall explained 43 and 13% of the variability in winter and spring wheat yields, respectively, compared to 2 and 1% for the previous year cover crop biomass. Further economic analyses are required to determine if the integration of livestock is necessary to mitigate the risks associated with the introduction of cover crops in replacement of fallow in the Northern Great Plains.


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