Global CA-CoP CONSERVATION AGRICULTURE COMMUNITY OF PRACTICE

for sustainable agriculture, land use and ecosystem management


Dear Subscribers,

Please see herebelow the April CA Newsletter from Cornell.

Apologies for any cross-posting.

Amir Kassam

Moderator

Global CA-CoP

e-mail: [log in to unmask]

URL: http://www.fao.org/conservation-agriculture


---------- Forwarded message ---------
From: Peter Hobbs <[log in to unmask]>
Date: Thu, 1 Apr 2021 at 15:07
Subject: April Cornell CA Scoopit newsletter
To: Amir Kassam <[log in to unmask]>


Dear Amir: Here is our April 2021 Conservation Agriculture Scoopit Research Update. You can also view online at https://www.scoop.it/topic/conservation-agriculture-by-conservation-ag?curate=true&null 
Can you send this out to people who get your listserv material? The hard copy is below.

An easier link to see all the research papers on CA is as follows:

Also, visit our main website at http://soilhealth.org for news and other CA information. Please use this link since we had to move our web site to a new server and this links takes you to the CA web site.

Conservation Agriculture Research Updates - April 2021
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This paper explains what "Regenerative Agriculture" is from an agronomist point of view. Why is it gaining such prominence? Which problems does it solve, and how? It has been promoted strongly by civil society and NGOs as well as by many of the major multi-national food companies. Many practices promoted as regenerative, including crop residue retention, cover cropping and reduced tillage are central to the canon of ‘good agricultural practices’, while others are contested and at best niche practices (e.g. permaculture, holistic grazing). The paper suggests RA represents a re-framing of what have been considered to be two contrasting approaches to agricultural futures, namely agroecology and sustainable intensification, under the same banner. More importantly, it draws attention away from more fundamental challenges.
The question whether NT systems are as productive as those relying on conventional tillage (CT) is a controversial issue, fraught by a high variability over time and space. This study expands existing datasets to include the results of the most recent field experiments, and we produce a global dataset comparing the crop yields obtained under CT and NT systems. In addition to crop yield, this dataset also reports information on crop growing season, management practices, soil characteristics and key climate parameters throughout the experimental year. The final dataset contains 4403 paired yield observations between 1980 and 2017 for eight major staple crops in 50 countries. The paper does discuss the results for NT versus CA, since the residue retention in the latter is important for success in some but not all situations and crops.
The objective of this study was to evaluate CA cropping systems for rainfed maize as an alternative to the traditional tillage-based cropping systems (CT) in the context of family farms, using a multi-criteria model that represents the point of view of farmers in Brazil. Farmers evaluated based on 5 criteria a) costs; b) yield; c) labor; d) human health and environment; and e) risks. CA did not differ from CT for the `costs' criterion but was superior for the `yield' and `labour' criteria. In contrast, CT obtained better ratings for the criteria `human health and environment' and `production risks'. Considering all criteria, CA was better appraised than CT. However, a new local policy measure that subsidizes the hiring of mechanized tillage services overturns this outcome, indicating the importance of exogenous factors. 
This study introduced CA to manage agro-ecosystems for improved and sustained productivity, and increased farmers’ profits while maintaining natural resources in rice-wheat systems of the IndoGangetic Plains of India. The project managed natural resources at the farm, village, and landscape scales to increase synergies between food production and ecosystem conservation. The results show that the CA-based rice-wheat (RW) system integrated with mungbean improved the system productivity by ∼10%, profitability by 20–30% using 15–30% less irrigation water, and 20–25% less energy input compared to conventional RW system in the IGP. Replacing rice with maize improved the productivity by 10-15% and profitability by 40–50% using ∼70% less irrigation water. CA layered with subsurface drip irrigation (SDI) in CA-based rice/maize systems recorded ∼5% higher system productivity and saved ∼50% of irrigation water compared to flood irrigation in CT-based systems. CA-based systems are found more adapted to extreme climatic conditions and can mitigate the negative effects of climatic stresses like terminal heat and water stress.
The UK launched a program to evaluate the extent to which on-farm mitigation measures can cost-effectively reduce the impacts of agricultural water pollution on river ecology whilst maintaining food production capacity. This study looked at the impacts on soil health of two types of conservation tillage (direct drill and shallow non-inversion) against conventional mouldboard ploughing after five years. Results revealed that conservation tillage alone is ineffective at improving the short-term environmental sustainability of farming practices in this lowland intensive arable setting and indicates that a broader, integrated approach to conservation agriculture is required incorporating aspects of cover cropping, crop rotations and precision farming techniques. The improvements in farm business performance do, however, demonstrate land managers can make important financial gains by converting to a conservation tillage system.
This study estimates the statistical effect of Conservation Agriculture on cropping-system yields (as opposed to single crops) under historical climate conditions. The cropping-system yields considered all crops grown including maize (Zea mays L.) and legumes in intercropping or rotation, or both. Data included 6296 yield observations from on-farm trials in farmer plots conducted over 14 seasons. This work studied three treatments: (1) a Control Practice treatment where the soil was tilled, crop residues were removed, and there was no crop species diversification, (2) a NT treatment where the soil was not tilled, crop residues were retained, and there was no crop species diversification, and (3) a CA treatment where the soil was not tilled, crop residues were retained, and there was crop species diversification through legume intercropping. The results demonstrate how CA can improve the adaptive capacity of cropping systems and this provides urgently needed evidence on how farmers can adapt to climate stress.
This is a corrected manuscript for this article that looks at crop diversification and intercropping in CA systems that have a direct impact on nutritional status of farm households due to a more diverse diet. This study from 2012-2020 assesses how the integration of grain legumes, cowpeas and soybeans, in maize-based CA systems either as intercrops or rotational crops affects maize grain yield and stability, total energy yield, protein yield and surplus calories after satisfying the daily requirement per household. Results show that intercropping compromises maize yields with marginal yield penalties of −5% compared to no-till monocropping. However, intercropped yields were more stable across environments.Total system caloric energy and protein yield were highest in intercropping systems due to higher productivity per unit land area owing to the additive contribution of both maize and legumes. 
This study assessed the impact of long-term conservation tillage and N fertilization in wheat-soybean rotation on soil aggregate distribution, nutrients stocks and functions of soil microorganisms. They compared conventional tillage and minimal tillage and 2 N levels; 0 and 200kgN/ha. Residues were incorporated to 25 cm in CT and 50% to 15cm in MT. Tillage was the most discriminant factor explaining 72% and 60% of total variance of soil parameters at 0-15 cm and 15-30 cm soil depth. All enzyme activities were higher under MT, whereas the majority of soil chemical parameters were higher under N200. They conclude that maintaining or even increasing SOC conservation in their silt loam soils may require both reduced tillage systems and N fertilization, shifting microbial community toward taxa more effective in contrasting soil degradation
This study reviewed the literature on benefits, trade-offs, adoption and adaptation of CA in sub-Saharan Africa. They show that benefits are inconsistent and there are trade-offs with crop residue use, weeds and insect pests, labour demands and short-term yield penalties despite CA improving soils and sustaining crop yields with generally low adoption in SSA. They suggest that adoption constraints include 1. the magnitude of transformation of management practices required by farmers moving to CA, 2. The multiple trade-offs associated with CA practices and 3. the incompatibility of CA practices to local conditions. They suggest focusing CA in Africa in places where it best fits and identifying and overcoming locally important trade-offs through adaptation and finding farm-specific optimal combinations in terms of feasibility and benefits.
This paper was chosen to show CA is viable for organic vegetable systems. Organic vegetable farmers are often dependent on tillage to incorporate crop residue, control weeds, and prepare seedbeds. Black, impermeable, polyethylene tarps applied on the soil surface and removed at planting can help suppress weeds before planting and reduce farmers' reliance on tillage. This study investigated the effects of tarp use and tarp duration on the soil environment, surface cover crop residue, and weed suppression to assess the efficacy of using tarps to improve reduced- and no-till practices for organic vegetable production in the US. They conclude that using tarps facilitates reduced and zero-till vegetables by providing a nutrient-rich and moist soil environment free of emerged weeds before planting without soil disturbance.





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