The weed species Spermacoce densiflora DC. and Spermacoce verticillata L. have shown an increase in their occurrence in cultivated areas in the northeast region of Brazil, and field observations have reported their ineffective control with chemicals. This study aimed to evaluate the germination of S. densiflora and S. verticillata under constant (15, 20, 25, 30 and 35°C) and alternating temperatures (20–30°C) in dark and in constant light; the emergence of seedlings from seven sowing depths (0, 0.5, 1, 2, 4, 6 and 10 cm); the emergence of seedlings under five types of cover crop straw (Crotalaria juncea L., Pennisetum glaucum (L.) R. Br., Sorghum bicolor (L.) Moench, Dolichos lablab L., and Cajanus cajan L.) and four amounts (nil and the average, half and twice the amount of straw produced in the field); and germination at different aqueous cover crop extract concentrations (0, 20, 40, 60 and 100%) to measure allelopathic potential of cover crop straw. The results showed that S. densiflora has positive photoblastic behavior. The alternating temperature provided the highest percentage of germination and germination speed index (GSI) for both species. S. densiflora and S. verticillata seedling emergence decreased with an increase in depth, with no germination at a depth of 10 cm. The presence of straw impaired the emergence of seedlings of S. densiflora and S. verticillata by delaying and even preventing germination from occurring. The gradual increase in the aqueous extract concentrations was accompanied by lower percentages of germination and GSI for S. densiflora and S. verticillata.

Declining nutrient densities of crops in the past 50–70 years have been attributed to unsound agricultural practices and plant breeding focus on yield rather than quality. Few studies have quantified the soil and nutritional quality of grains in organic and conventional farms and reported results are scarce and inconsistent. The Rodale Institute's Farming Systems Trial (FST) was established in 1981 to quantify the effects of long-term organic and conventional grain cropping systems and tillage practices. A 2014 study to quantify effects on the nutrient density of oat grains was integrated into three systems within the long-term trial: organic manure-based (MNR), organic legume-based (LEG), and conventional synthetic input-based (CNV), split between tilled (T) and no-till (NT) practices. Oat grains with hulls removed were analyzed for minerals (n = 24), vitamins (n = 24), amino acids (n = 24) and proteins (n = 24), while soil samples to a depth of 10 cm were analyzed for elemental minerals, and total carbon (C), nitrogen (N) and sulfur (S). Organic systems increased six out ten soil minerals whose concentrations were influenced by cropping systems: aluminum (Al), iron (Fe), chromium (Cr), calcium (Ca), barium (B) and strontium (Sr). All essential amino acids were greater in oat grains under LEG systems compared with other systems except lysine, histidine and methionine. Both LEG systems also increased 12 out of 13 non-essential amino acids in oat grains. Total oat N, C and S required for amino acid synthesis tended to be greater in organic systems. Soil N, C and S were highly correlated with total oat amino acids under organic systems compared to CNV. Organic LEG had significantly greater vitamin B1 than MNR and CNV. These results suggest that nutrient concentrations of oat grains were greater in organic systems compared to CNV systems, and the increase could be partially explained by the long-term soil management differences between the systems.

Biobased and biodegradable mulches (BDM) are a potentially sustainable alternative to polyethylene plastic mulch because they can be tilled into the soil at the end of the growing season. However, their degradation rate in the soil is uncertain, limiting their on-farm adoption. The objective of this study was to determine whether organic soil management practices could be leveraged to speed degradation of two potentially BDM across two diverse agroecoregions [Lincoln (LNK) and Scottsbluff (SBF), NE, USA]. Management treatments included compost, compost extract, cover crops, all three of these practices combined and a control. The two mulch types studied were a nonwoven polylactic acid fabric with embedded wood particles (PLA), and a starch-polyester mulch film (BLK). Mulches were applied in spring 2017 for vegetable production and removed in fall after harvest. Recovered mulch was sectioned into squares 10 cm2 and buried in mesh bags for 22 months. Mulch degradation, and soil chemical, physical and biological properties were measured at four times over 2 years. Management treatments applied seasonally across 2 years led to expected changes in soil properties, yet they had no effect on mulch degradation. Instead, mulch degradation was driven by the interaction of location and mulch type. The BLK mulch had degraded by 98% at LNK after 12 months, but only by half after 22 months at SBF. Degradation of PLA after 22 months was similar between locations with 29 ± 4% mulch mass remaining at SBF and 33 ± 4% remaining at LNK. Climate and soil characteristics at each location were strong determinants of mulch degradation. Specifically, soils at LNK were finer textured, lower in pH, higher in soil water content, organic matter and nitrates, and with greater bacterial abundance compared to SBF. The strong location by mulch type interaction observed could inform the development of regionally specific predictive models of degradation.

This paper aims to assess young farmers' willingness to adopt sustainable agriculture (SA) by implementing the expanded theory of planned behavior (TPB) within the northern region of Bangladesh. The outcomes attained specified that attitudes toward SA, perceived behavior control and perceived self-identity have progressive and fundamental impacts on adoption behavior and affect farmers' intentions to adopt SA's particular production mechanism. On the other hand, the social interface view toward SA is not significantly associated with the Bangladeshi farmer's adoption intention. The results also show that interconnections between social and familial pressure are not significant for sustainable farming practice adoption intentions. However, the interconnections among the psychosocial factors have a crucial role in formulating the TPB to forecast the intentional behavior for adopting SA practices. Thus, the government should highlight the advantages of several sustainable agricultural practices and circulate more detailed information regarding SA tactics to improve the knowledge gap of smallholder farmers. Furthermore, training facilities should be extended to improve the attitude and perceived self-identity of young farmers. Moreover, the formulation of structural information sharing platforms and agricultural value chain facilities should also help shape young farmers' interpersonal behavior in adopting SA practices.

Conservation agriculture (CA) is an important technology in many developing countries for increasing smallholder agricultural productivity and conserving arable soils. This study focuses on the effect of CA on smallholder household wellbeing including productive assets, livestock and housing material quality. The study uses a survey of CA adopters and non-adopters in the Tete and Barue districts of Mozambique. Propensity score matching was used to develop two counterfactual groups; (1) non-adopters in the communities that had received technical assistance on implementing CA, and (2) non-adopting households in communities that had not received CA instruction. Results suggest that CA adopters realized higher levels of farm production assets and better quality housing materials. CA adoption had no association with livestock ownership. The findings are encouraging with respect to demonstrating the relationship between CA adoption and improvements in smallholder household wellbeing.

Climate change and soil fertility decline are major threats to smallholder farmers' food and nutrition security in southern Africa, and cropping systems that improve soil health are needed to address these challenges. Cropping systems that invest in soil organic matter, such as no-tillage (NT) with crop residue retention, have been proposed as potential solutions. However, a key challenge for assessing the sustainability of NT systems is that soil carbon (C) stocks develop over long timescales, and there is an urgent need to identify trajectory indicators of sustainability and crop productivity. Here we examined the effects of NT as compared with conventional tillage without residue retention on relationships between soil characteristics and maize (Zea mays L.) productivity in long-term on-farm and on-station trials in Zimbabwe. Our results show that relationships between soil characteristics and maize productivity, and the effects of management on these relationships, varied with soil type. Total soil nitrogen (N) and C were strong predictors of maize grain yield and above-ground biomass (i.e., stover) in the clayey soils, but not in the sandy soils, under both managements. This highlights context-specific benefits of management that fosters the accumulation of soil C and N stocks. Despite a strong effect of NT management on soil C and N in sandy soils, this accrual was not sufficient to support increased crop productivity in these soils. We suggest that sandy soils should be the priority target of NT with organic resource inputs interventions in southern Africa, as mineral fertilizer inputs alone will not halt the soil fertility decline. This will require a holistic management approach and input of C in various forms (e.g., biomass from cover crops and tree components, crop residues, in combination with mineral fertilizers). Clayey soils on the other hand have greater buffering capacity against detrimental effects of soil tillage and low C input.

Legume green manures (GM) are a vital source of nitrogen (N) for many organic grain systems. A common practice among organic growers is to undersow clover into a small grain, harvest the grain crop and terminate the clover stand in late fall by moldboard plowing in preparation for a cash crop the following spring. While fall plowing offers excellent clover kill, growers increasingly seek an alternative termination method that reduces tillage intensity and bare winter soil. This study, performed at two sites in Maine, evaluates three clover termination methods for kill efficacy, winter soil cover, spring soil conditions and N uptake and grain yield and protein of a subsequent test crop of hard red spring wheat (Triticum aestivum L., var. Glenn). Red clover (Trifolium pratense L.) was intercropped with spring barley (Hordeum vulgare L.) and terminated in late fall by moldboard plowing (PL), skim plowing (SK) or undercutting (UC). A control treatment received no clover and was fall plowed. An additional treatment, winterkilled field peas (WK), was evaluated at one site. SK, UC and WK increased soil cover relative to PL, though UC resulted in low clover kill efficacy in a wet spring and is in need of improved design. Grain yield was higher following red clover compared to the no-clover control at one site, but was unaffected by termination method. At one site, grain crude protein was higher following PL than the other treatments, indicating the possibility for more favorable timing of N availability associated with PL.