Direct Seeding Mulch-based Cropping Research Articles

Impact of a conservation agriculture system on soil characteristics, rice yield, and root-parasitic nematodes in a Cambodian lowland rice field

Abstract Rice production in Southeast Asia is significantly affected by root-parasitic nematodes (RPN). The Green Revolution has encouraged new agricultural practices (e.g. intensive monoculture, high yielding rice variety) to respond to the high rice demand; however, these methods have promoted the spread of these pests. The recent banning of chemical nematicides resulted in a need for alternative sustainable control strategies. In the present study, we assessed the effects of a direct-seeding mulch-based cropping system (DMC) vs conventional plough-based tillages (CT) on soil properties, rice yield and RPN communities during a two-year trial in Cambodia. Our results show that on average the population densities of RPN were significantly higher in DMC than in CT. Molecular identification revealed only two RPN species associated with roots: Meloidogyne graminicola, not previously reported from Cambodia, was predominant and was present throughout the plant’s development, whereas Hirschmanniella mucronata was only found at the tillering and milky stages. We conclude that DMC had a significant positive impact on rice yield, despite higher RPN short-term pressure. In order to increase the efficiency of such cropping systems, further studies and an evaluation of the long-term relationships between DMC, the nature of cover crops used, the soil biota including RPN, and rice yield should be conducted.

Economic assessment of conservation agriculture options in mixed crop-livestock systems in Brazil using farm modelling

Direct seeding mulch-based cropping (DMC) systems are often considered as an efficient way of combining ecological sustainability and economic viability while maintaining or increasing agricultural productivity. This paper describes a modelling analysis of the functioning of family farms in rural settlements of the agrarian reform in the Cerrados of Brazil. The aim was to assess the impact of the introduction of DMC systems with and without cover crops on crop-livestock management and net household income. A bio-economic farm model based on optimization of a utility function under multiple constraints was developed, capturing the interactions between livestock activities and the introduction of DMC systems. The model was run for six farms representing three farm types in the study area: 1) subsistence-oriented mixed crop-livestock farms; 2) market-oriented dairy farms; and 3) mixed crop-livestock farms, oriented to meat marketing. The following maize-based DMC systems were evaluated: a DMC system with mulch from residues of the previous maize crop and no cover crop, and two DMC systems with a fodder species, Brachiaria brizanta or Cajanus cajan, as cover crop. The simulated adoptability of DMC systems by farmers of the assentamentos depended to a large extent on the yields and feed quality of the fodder species. The modelling results suggested that DMC with C. cajan as cover crop was the best suitable option for all simulated farm types. This was mainly explained by its high feed value (expressed in crude protein content). Furthermore, in the process of intensification and specialization in dairy production, farmers were likely to shift from using maize for pig husbandry to feeding it to the dairy cows. The introduction of cover crops in the farm systems was a source of additional animal feed during the dry season that was cheaper than the purchase of feed concentrates, when the size of the dairy herd did not exceed a certain threshold.

Use of No-till System on Straw by Cotton Producers in Cameroon

Field surveys using questionnaires administered among cotton producers semi-openly were done in three cotton zone of Cameroon, Lainde Massa in the North, Kilwo in the Far North and Tapi in the Adamaoua regions. The objective of this study was to evaluate the degree of appropriation of directseeding mulch-based cropping (DMC) systems, identify the problems that influence this appropriation and the consequences of no-appropriation in the cotton zone of Cameroon. The result showed that producers of the study sites were facing several difficulties which impeded the appropriation of DMC systems. These difficulties were landownership issues, financial difficulties resulting in significant financial means necessary for the implementation of DMC systems, the decrease in a radical way of subsidies from the ESA (Eau-Sol-Arbre) project, the difficulty in repayment of loans contracted during agricultural campaigns at the SODECOTON and high land rental costs. The consequences of no-appropriation of DMC systems were the continuous degradation of agricultural soils and decline in soil fertility, due to the acceleration of water and wind erosion, the clean of fields by fire and the practice of inappropriate farming techniques. The model of

Short-Term Effects of Conversion to Direct Seeding Mulch-Based Cropping Systems on Macro-Fauna and Weed Dynamics

ABSTRACTAgroecosystem biodiversity could provide essential services such as pest control. One approach currently used to promote ecosystem services in agricultural systems is to reduce tillage and increase plant diversity. In this study, we assessed the short-term effects of conversion from reduced tillage (RT) to direct seeding mulch-based cropping systems (DMC) on the dynamics of arthropods (detritivores and predators), and major pests (slugs and weeds). The study was conducted in two commercial fields: one cropped with sorghum (Sorghum bicolor L.) and one with maize (Zea mays L.). We found that both beneficial and detrimental groups monitored were more abundant in DMC than in RT treatment and that the dominant species differed between treatments. Because of their major role in agroecosystems by contributing to the control of weed seeds, insects, and slugs, carabid beetles (Carabidae) were investigated in greater detail, and the results showed their diversity was also higher in DMC than in RT. The dominant species found were Poecillus cupreus and Pseudofonus rufipes in the maize and sorghum fields, respectively. The increase in biological control agents shortly after conversion suggested that cover crops should be considered as a pest management tool, even on a short-term scale.

Impact of land management system on crop yields and soil fertility in Cameroon

Abstract. The impact of direct-seeding mulch-based cropping systems (DMC), direct seeding (DS) and tillage seeding (TS) on Sorghum yields, soil fertility and the rehabilitation of degraded soils was evaluated in northern Cameroon. Field work consisted of visual examination, soil sampling, yield and rainfall data collection. Three fertilization rates (F1: 100 kg ha−1 NPK + 25 kg ha−1 of urea in DMC, F2: 200 kg ha−1 NPK + 50 kg ha−1 of urea in DMC and F3: 300 kg ha−1 NPK + 100 kg ha−1 of urea in DMC) were applied to each cropping system (DS, TS and DMC), resulting in nine experimental plots. Two types of chemical fertilizer were used (NPK 22.10.15 and urea) and applied each year from 2002 to 2012. Average Sorghum yields were 1239, 863 and 960 kg ha−1 in DMC, DS and TS, respectively, at F1, 1658, 1139 and 1192 kg ha−1 in DMC, DS and TS, respectively, at F2, and 2270, 2138 and 1780 kg ha−1 in DMC, DS and TS, respectively, at F3. pH values were 5.2–5.7 under DMC, 4.9–5.3 under DS and TS and 5.6 in the control sample. High values of cation exchange capacity were recorded in the control sample, TS system and F1 of DMC. Base saturation rates, total nitrogen and organic matter contents were higher in the control sample and DMC than in the other systems. All studied soils were permanently not suitable for Sorghum due to the high percentage of nodules. F1 and F2 of the DS were currently not suitable, while F1 and F3 of DMC, F3 of DS and F1, F2 and F3 of TS were marginally suitable for Sorghum due to low pH values.

Short-Term Effects of Conversion from Reduced Tillage to Direct-Seeding Mulch-Based Cropping Systems

Conservation tillage is one strategy whereby both sustainability and productivity can be achieved by improving the soil quality. Although reduced tillage (RT) is widely practiced, more conservative strategies, such as direct-seeding mulch-based cropping systems (DMC), are less frequent. Here we assessed the effect of conversion from RT to DMC in three commercial fields in southern France (inland Mediterranean climate). Two fields were cropped with maize (Zea mays L.) and one with sorghum (Sorghum bicolor L.), and monitored during 15 months. We found higher soil water potential retention in DMC than in RT at 10, 30, and 60 cm soil depth. Conversely, nitrogen availability was slightly higher in the RT treatment. Crop development was not affected by the soil practices, but crop yields were higher in the DMC treatment for one maize field and the sorghum field (plus 3.04 t/ha harvested in the DMC treatment when compared to the RT treatment in the maize field and plus 2.105 t/ha in the sorghum one). This study demonstrates that DMC can provide short-term benefits in farm fields in southern France, but these benefits are not automatic and the conditions under which they are obtained remain to be clarified.

Protection of Upland Rice at Lake Alaotra (Madagascar) from Black Beetle Damage (Heteronychus plebejus) (Coleoptera: Dynastidae) by Seed Dressing

In Madagascar, growing demand for rice and resulting increased pressure on inundated lands has favoured the cultivation of upland rain-fed rice on hill slopes. Due to the instability of the ecosystem, this type of agriculture cannot meet the objectives of both sustainability and high yields if conventional tillage is used, particularly due to high erosion risk. Direct seeding, mulch-based cropping (DMC) systems have opened new prospects for upland rice.

Constraints to farmers’ adoption of direct-seeding mulch-based cropping systems: A farm scale modeling approach applied to the mountainous slopes of Vietnam

Substantial initiatives are under way in the tropical world to develop and promote direct-seeding mulch-based cropping systems (DMC) in order to reduce soil erosion and improve crop nutrient and water balances. DMC have been adopted by large-scale mechanized farmers, especially in America and Australia, but seldom by resource-poor farmers in the developing world. This study was conducted in Vietnam with the aim of evaluating the feasibility of farmers’ implementing DMC in a mountainous area. The method involved simulation of rational households maximizing their income subject to food security constraints and availability of resources. It generated insight into why farmers of a small region were reluctant to adopt DMC due to the extra labor and input required to implement these techniques during the first years, which hampers their economic performance. In another region, under different biophysical and economic environmental conditions, the study showed that DMC were more likely to be adopted provided that possible constraints at the community level are overcome. The method also allowed us to discuss the types of technical improvements that would make DMC more attractive to farmers. For most farm types, labor required by mulch establishment would have to be reduced by more than 30%. This would mean spreading much less biomass than the 7 t ha −1 currently necessary, compromising the weed-control function of mulch. This would be technically feasible only by using herbicides but this would not be economically sound since it would increase cash requirements. The study showed that subsidies of 50 to more than 200 USD ha −1 were necessary to enable the conversion of all conventionally managed sloping land into DMC in the simulations. These amounts are high relatively to gross margins (250–750 USD ha −1) under conventional management.

Cover Crop and Nitrogen Effects on Maize Productivity in No‐Tillage Systems of the Brazilian Cerrados

Cover crops in direct seeding mulch‐based cropping (DMC) systems can be an effective tool to optimize N management for crop production in the Brazilian cerrados. The objective of this study was to determine the effect of four cover crops on maize (Zea mays L.) grain yields in two fields that had been under DMC for 3 and 14 yr. We hypothesized that cover crops would optimize N supply to the maize crop, thereby leading to increased yields. Cover crop treatments were: bare fallow (BF), pigeon pea (PP) [Cajanus cajan (L.) Huth], pearl millet [Pennisetum glaucum (L.) R. Br.]–Congo signal grass (PM‐CS) (Brachiaria ruziziensis Germain & Evrard), pigeon pea–finger millet (PP‐FM) [Eleusine coracana (L.) Gaertn.], and sorghum (S) [Sorghum bicolor (L.) Moench]. Experiments were conducted during the 2003–2004 and 2004–2005 growing seasons. In 2003–2004 on the DMC‐14 field, cover crops increased N uptake of zero‐N fertilized maize with 25 to 66 kg N ha−1 compared to BF, which resulted in an increase in grain yield of 0.4 to 2.4 Mg ha−1. Effects on fertilized maize were much less. The highest yield benefits were obtained with pigeon pea and sorghum as sole cover crop. No significant cover crop effects were recorded in 2004–2005. Nitrogen losses under maize estimated on the basis of a simple soil mineral nitrogen balance ranged from 40 to 90 kg N ha−1 in 2003–2004, while they were smaller in 2004–2005 (10–25 kg N ha−1), presumably due to the lower rainfall. Cover crops can have an immediate positive effect on maize productivity under DMC in the cerrados, provided that they are sown immediately after harvest of the main crop.

Direct seeding mulch-based cropping increases both the activity and the abundance of denitrifier communities in a tropical soil

This study evaluated the impact of direct seeding mulch-based cropping (DMC), as an alternative to conventional tilling (CT), on a functional community involved in N cycling and emission of greenhouse gas nitrous oxide (N 2O). The study was carried out for annual soybean/rice crop rotation in the Highlands of Madagascar. The differences between the two soil management strategies (direct seeding with mulched crop residues versus tillage without incorporation of crop residues) were studied along a fertilization gradient (no fertilizer, organic fertilizer, organic plus mineral fertilizers). The activity and size of the denitrifier community were determined by denitrification enzyme activity assays and by real-time PCR quantification of the denitrification genes. Denitrification activity and total C and N content in the soil were significantly increased by DMC both years, whereas the fertilization regime and sampling year (crop and mulch types, climatic conditions) had very little effect. Similar results were also observed for denitrification gene densities. Denitrification enzyme activity was more closely correlated with C content than with N content in the soil and denitrification gene densities. Principal component analysis confirmed that soil management had the strongest impact on the soil denitrifier community and total C and N content for both years and further indicated that changes in microbial and chemical soil parameters induced by the use of fertilizer were favored in DMC plots. Overall, the alternative DMC system had a significant positive effect on denitrifier densities and potential activities, which was not altered by crop rotation and the level of fertilization. These data also suggest that in these clayey soils, the DMC system simultaneously increased the size of the soil N pool and accelerated the N cycle, by stimulating the denitrifier community. Complementary investigations should further determine in greater detail the influence of DMC on in situ N-fluxes caused by denitrification.

Differential Responses of Nitrate Reducer Community Size, Structure, and Activity to Tillage Systems

The main objective of this study was to determine how the size, structure, and activity of the nitrate reducer community were affected by adoption of a conservative tillage system as an alternative to conventional tillage. The experimental field, established in Madagascar in 1991, consists of plots subjected to conventional tillage or direct-seeding mulch-based cropping systems (DM), both amended with three different fertilization regimes. Comparisons of size, structure, and activity of the nitrate reducer community in samples collected from the top layer in 2005 and 2006 revealed that all characteristics of this functional community were affected by the tillage system, with increased nitrate reduction activity and numbers of nitrate reducers under DM. Nitrate reduction activity was also stimulated by combined organic and mineral fertilization but not by organic fertilization alone. In contrast, both negative and positive effects of combined organic and mineral fertilization on the size of the nitrate reducer community were observed. The size of the nitrate reducer community was a significant predictor of the nitrate reduction rates except in one treatment, which highlighted the inherent complexities in understanding the relationships the between size, diversity, and structure of functional microbial communities along environmental gradients.

Long-term effects of continuous direct seeding mulch-based cropping systems on soil nitrogen supply in the Cerrado region of Brazil

In the Cerrado region of Brazil conventional soybean monoculture is since the 1980s being replaced by direct seeding mulch-based cropping (DMC) with two crops per year and absence of tillage practices. The objective of this study was to assess the long-term impact of DMC on soil organic matter accumulation and nitrogen (N) mineralization. Measurements of soil organic carbon (C) content, soil total N content and soil N mineralization, both under laboratory conditions using disturbed soil samples and under field conditions using intact soil cores were conducted on a chronosequence of 2-, 6-, 9- and 14-year-old DMC fields (DMC-2, DMC-6, DMC-9 and DMC-14, respectively). The average increase of organic C in the 0–30 cm topsoil layer under DMC was 1.91 Mg C ha−1 year−1. Soil total N increased with 103 kg N ha−1 year−1 (0–30 cm). The potential N mineralization rate under laboratory conditions (28°C, 75% of soil moisture at field capacity) was 0.27, 0.28, 0.39 and 0.36 mg N kg soil−1 day−1 for, respectively, the DMC-2, DMC-6, DMC-9 and DMC-14 soils. The corresponding specific N mineralization rates were 0.16, 0.15, 0.22 and 0.17 mg N g N−1 day−1. There was no obvious explanation for the higher specific N mineralization rate of soils under DMC-9, given the similar soil conditions and land-use history before DMC was introduced. Results from the in situ N incubation experiments were in good agreement with those from the laboratory incubations. We estimated that soil N mineralization increases with about 2.0 kg N ha−1 year−1 under DMC. The increase was mainly attributed to the larger soil total N content. These results indicate that even in the medium term (10 years), continuous DMC cropping has limited implications for N fertilization recommendations, since the extra soil N supply represents less than 20% of the common N fertilization dose for maize in the region.

Earthworm activity affects soil aggregation and organic matter dynamics according to the quality and localization of crop residues—An experimental study (Madagascar)

Soil organic matter (SOM) plays a central role in the functioning of ecosystems, and is beneficial from agronomic and from environmental point of view. Alternative cultural systems, like direct seeding mulch-based cropping (DMC) systems, enhance carbon (C) sequestration in agricultural soils and lead to an increase in soil macrofauna. This study aimed at evaluating in field mesocosms the effects of earthworms on SOM dynamics and aggregation, as influenced by residue quality and management. In the highlands of Madagascar, buckets were filled with 2 mm-sieved clayey Inceptisol. The effects of earthworm addition ( Pontoscolex corethrurus), residue addition (rice, soybean, and no addition), and localization of the residues (mulched or buried) were studied. After 5 months, soil from mesocosms with earthworms had significantly lower C concentration and higher proportion of large water-stable macroaggregates (>2000 μm) than those without earthworms, because of the production of large macroaggregates by earthworms. Earthworm effect on soil aggregation was greater with rice than with soybean residues. Casts (extracted from mesocosms with earthworms) were slightly enriched in C and showed significantly higher mineralization than the non-ingested soil (NIS), showing that at the time scale of our study, the carbon contained in the casts was not protected against mineralization. No difference in microbial biomass was found between casts and NIS. Complementary investigations are necessary to assess long-term effects of earthworm addition on SOM dynamics, the conditions of occurrence of physical protection, and the impact of earthworms on the structure of the microbial community.

Soil carbon storage potential of direct seeding mulch‐based cropping systems in the Cerrados of Brazil

AbstractNo‐tillage cropping systems with direct seeding into a mulch of plant residues from cover crops – the so‐called direct seeding mulch‐based cropping (DMC) systems – have been adopted widely over the last 10–15 years in the Cerrado region of Brazil. They are replacing the traditional soybean monoculture with bare fallow using conventional tillage (CT) practices. The objective of this study was to examine how DMC practices affect soil organic carbon (SOC) dynamics and to assess their potential for enhanced soil carbon (C) storage. The approach was to determine soil C stocks along a chronosequence of fields under DMC, and then to apply the generic decomposition and yield (G'DAY) plant–soil model to analyse the soil C storage potential for a number of cropping systems. Forty‐five fields were selected on a plateau of Ferralsols in the central Cerrado region to represent a chronosequence of 0–12 years under continuous DMC. Before DMC the fields had been under CT soybean monoculture following the clearing of the native savannah. An average increase in SOC stocks of 0.83 Mg C ha−1 yr−1 in the 0–20 cm topsoil was measured. The corresponding increase in total soil nitrogen was 79 kg N ha−1 yr−1. The G'DAY model predicted a net accumulation of 0.70–1.15 Mg C ha−1 yr−1 in the 0–40 cm topsoil for the first 12 years, depending on the type of soil and DMC system. Model predictions showed that less soil C was accumulated under DMC systems that commenced immediately after clearing the native savannah. Gains in soil C under DMC were primarily due to the introduction of a second crop that caused higher net primary productivity, leading to higher plant C inputs to soil. A rough estimation shows that the conversion of 6 million ha of CT soybean monoculture to DMC in the Cerrados would enhance soil C storage by 4.9 Tg C yr−1 during at least the first 12 years following the conversion to DMC.